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  • How to speed up a slow UPDATE query

    - by Mike Christensen
    I have the following UPDATE query: UPDATE Indexer.Pages SET LastError=NULL where LastError is not null; Right now, this query takes about 93 minutes to complete. I'd like to find ways to make this a bit faster. The Indexer.Pages table has around 506,000 rows, and about 490,000 of them contain a value for LastError, so I doubt I can take advantage of any indexes here. The table (when uncompressed) has about 46 gigs of data in it, however the majority of that data is in a text field called html. I believe simply loading and unloading that many pages is causing the slowdown. One idea would be to make a new table with just the Id and the html field, and keep Indexer.Pages as small as possible. However, testing this theory would be a decent amount of work since I actually don't have the hard disk space to create a copy of the table. I'd have to copy it over to another machine, drop the table, then copy the data back which would probably take all evening. Ideas? I'm using Postgres 9.0.0. UPDATE: Here's the schema: CREATE TABLE indexer.pages ( id uuid NOT NULL, url character varying(1024) NOT NULL, firstcrawled timestamp with time zone NOT NULL, lastcrawled timestamp with time zone NOT NULL, recipeid uuid, html text NOT NULL, lasterror character varying(1024), missingings smallint, CONSTRAINT pages_pkey PRIMARY KEY (id ), CONSTRAINT indexer_pages_uniqueurl UNIQUE (url ) ); I also have two indexes: CREATE INDEX idx_indexer_pages_missingings ON indexer.pages USING btree (missingings ) WHERE missingings > 0; and CREATE INDEX idx_indexer_pages_null ON indexer.pages USING btree (recipeid ) WHERE NULL::boolean; There are no triggers on this table, and there is one other table that has a FK constraint on Pages.PageId.

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  • After creating a mysql user with all privileges, the user cannot create databases in phpMyAdmin and only sees information_schema table

    - by GHarping
    This is a recurring problem for some reason... Using mysql 5.5, I am simply trying to create a user that can connect to the database remotely, have access to all databases, and create databases. I have created a user using: create user 'dev'@'%' identified by 'abcdefg'; then granted all permissions using: GRANT ALL ON *.* to 'dev'@'192.168.%' IDENTIFIED BY 'abcdefg' WITH GRANT OPTION; and the result is that the user cannot create databases, and can only see information_schema database for some reason. Databases Create database: Documentation No Privileges Database Ascending information_schema Total: 1 Does anyone know why this might be happening?

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  • Rendering partial for table row with form_tag is getting crazy!

    - by xopht
    I have 23(column)x6(row) table and change the row with link_to_remote function. each tr tag has its own id attribute. change link call change action and change action changes the row using render function wit partial. _change.html.erb <td id="row_1">1</td> . . omitted . . <td id="row_23">23</td> link_to_remote function <%= link_to_remote 'Change', :update => 'row_1', :url => change_path %> change action def change logger.debug render :partial => 'change' end If I coded like above, everything work okay. This means all changed-columns are in one row. But, if I wrap partial code with *form_for* function like below... <% form_for 'change' do %> <td id="row_1">1</td> . . omitted . . <td id="row_23">23</td> <% end %> Then, one column located in one row and that column is the first column. I've looked up the log file, but it was normal html tags. What's wrong?

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  • Adding a footer to a table in another view?

    - by cannyboy
    The app I'm making has a settings view which I want to show on the first run of the app. Normally (after the first run) this view will be pushed onto the screen and there will be a "Back" button in the nav bar. However, on first launch I don't want there to be a back button. Instead, I want to add a 'Done' button at the footer of the table... and then the view can be popped. Here's my code (in my initial view's viewDidLoad). I have removed the back button, but don't know how to add the footer and button. NSUserDefaults *prefs = [NSUserDefaults standardUserDefaults]; if ([prefs stringForKey:@"firstRun"] == nil) { SettingsViewController *settingsView = [[SettingsViewController alloc] initWithNibName:@"SettingsView" bundle:nil]; settingsView.hidesBottomBarWhenPushed = YES; settingsView.navigationItem.hidesBackButton = TRUE; // add footer button here? [[self navigationController] pushViewController:settingsView animated:YES]; [settingsView release]; [prefs setObject:@"OK" forKey:@"firstRun"]; } else { //something }

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  • Fetching only the first record in the table (via the view) without changing controller?

    - by bgadoci
    I am trying to only fetch the first record in my table for display. I am creating a site where a user can upload multiple images and attach to a post but I only want to display the first image view for each post. For further clarification posts belong_to projects. So when you are on the projects show page you see multiple posts. In this view I only want to display the first image for each post. Is there a way to do this in the view without affecting the controller (as later I want to allow users to browse all photos through the addition of a lightbox). Here is my /views/posts/_post.html.erb code: <% div_for post do %> <% post.photos.each do | photo | %> <%= image_tag(photo.data.url(:large), :alt => '') %> <%= photo.description %> <% end unless post.photos.first.new_record? rescue nil %> <%= link_to h(post.link_title), post.link %> <%= h(post.description) %> <%= link_to 'Manage this post', edit_post_path(post) %> <% end %> UPDATE: I am using a photos model to attach multiple photos to each post and using paperclip here.

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  • Hibernate CreateSQL Query Problem

    - by Shaded
    Hello All I'm trying to use hibernates built in createsql function but it seems that it doesn't like the following query. List =hibernateSession.createSQLQuery("SELECT number, location FROM table WHERE other_number IN (SELECT f.number FROM table2 AS f JOIN table3 AS g on f.number = g.number WHERE g.other_number = " + var + ") ORDER BY number").addEntity(Table.class).list(); I have a feeling it's from the nested select statement, but I'm not sure. The inner select is used elsewhere in the code and it returns results fine. This is my mapping for the first table: <hibernate-mapping> <class name="org.efs.openreports.objects.Table" table="table"> <id name="id" column="other_number" type="java.lang.Integer"> <generator class="native"/> </id> <property name="number" column="number" not-null="true" unique="true"/> <property name="location" column="location" not-null="true" unique="true"/> </class> </hibernate-mapping> And the .java public class Table implements Serializable { private Integer id;//panel_facility private Integer number; private String location; public Table() { } public void setId(Integer id) { this.id = id; } public Integer getId() { return id; } public void setNumber(Integer number) { this.number = number; } public Integer number() { return number; } public String location() { return location; } public void setLocation(String location) { this.location = location; } } Any suggestions? Edit (Added mapping)

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  • Set bounds for markers generated by jQuery table loop?

    - by abemonkey
    I have some jQuery code that goes through a table of location results and puts corresponding pins on a map. I am having trouble figuring out how to set the bounds so that when it goes through the loop and generates the markers on the map that it zooms and pans to fit the markers in the view. I've tried implementing code from some similar questions on this site but nothing seems to be working. Please let me know what code I should be using and where the heck I should put it in my script: $(function() { var latlng = new google.maps.LatLng(44, 44); var settings = { zoom: 15, center: latlng, disableDefaultUI: false, mapTypeId: google.maps.MapTypeId.ROADMAP }; var map = new google.maps.Map(document.getElementById("map_canvas"), settings); $('tr').each(function(i) { var the_marker = new google.maps.Marker({ title: $(this).find('.views-field-title').text(), map: map, clickable: true, position: new google.maps.LatLng( parseFloat($(this).find('.views-field-latitude').text()), parseFloat($(this).find('.views-field-longitude').text()) ) }); var infowindow = new google.maps.InfoWindow({ content: $(this).find('.views-field-title').text() + $(this).find('.adr').text() }); new google.maps.event.addListener(the_marker, 'click', function() { infowindow.open(map, the_marker); }); }); }); `

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  • Function to extract data in insert into satement for a table.

    - by user269484
    Hi...I m using this Function to extract the data but unable to extract LONG datatype. Can anyone help me? create or replace Function ExtractData(v_table_name varchar2) return varchar2 As b_found boolean:=false; v_tempa varchar2(8000); v_tempb varchar2(8000); v_tempc varchar2(255); begin for tab_rec in (select table_name from user_tables where table_name=upper(v_table_name)) loop b_found:=true; v_tempa:='select ''insert into '||tab_rec.table_name||' ('; for col_rec in (select * from user_tab_columns where table_name=tab_rec.table_name order by column_id) loop if col_rec.column_id=1 then v_tempa:=v_tempa||'''||chr(10)||'''; else v_tempa:=v_tempa||',''||chr(10)||'''; v_tempb:=v_tempb||',''||chr(10)||'''; end if; v_tempa:=v_tempa||col_rec.column_name; if instr(col_rec.data_type,'CHAR') 0 then v_tempc:='''''''''||'||col_rec.column_name||'||'''''''''; elsif instr(col_rec.data_type,'DATE') 0 then v_tempc:='''to_date(''''''||to_char('||col_rec.column_name||',''mm/dd/yyyy hh24:mi'')||'''''',''''mm/dd/yyyy hh24:mi'''')'''; else v_tempc:=col_rec.column_name; end if; v_tempb:=v_tempb||'''||decode('||col_rec.column_name||',Null,''Null'','||v_tempc||')||'''; end loop; v_tempa:=v_tempa||') values ('||v_tempb||');'' from '||tab_rec.table_name||';'; end loop; if Not b_found then v_tempa:='-- Table '||v_table_name||' not found'; else v_tempa:=v_tempa||chr(10)||'select ''-- commit;'' from dual;'; end if; return v_tempa; end; /

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  • How to handle product ratings in a database

    - by Mel
    Hello, I would like to know what is the best approach to storing product ratings in a database. I have in mind the following two (simplified, and assuming a MySQL db) scenarios: Scenario 1: Create two columns in the product table to store number of votes and the sum of all votes. Use columns to get an average on the product display page: products(productedID, productName, voteCount, voteSum) Pros: I will only need to access one table, and thus execute one query to display product data and ratings. Cons: Write operations will be executed in a table whose original purpose is only to furnish product data. Scenario 2: Create an additional table to store ratings. products(productID, productName) ratings(productID, voteCount, voteSum) Pros: Isolate ratings into a separate table, leaving the products table to furnish data on available products. Cons: I will have to execute two separate queries on product page requests (one for data and another for ratings). In terms of performance, which of the following two approaches is best: Allow users to execute an occasional write query to a table that will handle hundreds of read requests? Execute two queries at every product page, but isolate the write query into a separate table. I'm a novice to database development, and often find myself struggling with simple questions such as these. Many thanks,

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  • mysql join with conditional

    - by Conor H
    Hi There, I am currently working on a MySQL query that contains a table: TBL:lesson_fee -fee_type_id (PRI) -lesson_type_id (PRI) -lesson_fee_amount this table contains the fees for a particular 'lesson type' and there are different 'fee names' (fee_type). Which means that there can be many entries in this table for one 'lesson type' In my query I am joining this table onto the rest of the query via the 'lesson_type' table using: lesson_fee INNER JOIN (other joins here) ON lesson_fee.lesson_type_id = lesson_type.lesson_type_id The problem with this is that it is currently returning duplicate data in the result. 1 row for every duplicate entry in the 'lesson fee' table. I am also joining the 'fee type' table using this 'fee_type_id' Is there a way of telling MySQL to say "Join the lesson_fee table rows that have lesson_fee.lesson_type_id and fee_type_id = client.fee_type_id". UPDATE: Query: SELECT lesson_booking.lesson_booking_id,lesson_fee.lesson_fee_amount FROM fee_type INNER JOIN (lesson_fee INNER JOIN (color_code INNER JOIN (employee INNER JOIN (horse_owned INNER JOIN (lesson_type INNER JOIN (timetable INNER JOIN (lesson_booking INNER JOIN CLIENT ON client.client_id = lesson_booking.client_id) ON lesson_booking.timetable_id = timetable.timetable_id) ON lesson_type.lesson_type_id = timetable.lesson_type_id) ON horse_owned.horse_owned_id = lesson_booking.horse_owned_id) ON employee.employee_id = timetable.employee_id) ON employee.color_code_id = color_code.color_code_id) ON lesson_fee.lesson_type_id = lesson_type.lesson_type_id) ON lesson_fee.fee_type_id = client.fee_type_id WHERE booking_date = '2010-04-06' ORDER BY lesson_booking_id ASC How do I keep the format(indentation) of my query?

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  • What is preferred method for searching table data using stored procedure?

    - by Mourya
    I have a customer table with Cust_Id, Name, City and search is based upon any or all of the above three. Which one Should I go for ? Dynamic SQL: declare @str varchar(1000) set @str = 'Select [Sno],[Cust_Id],[Name],[City],[Country],[State] from Customer where 1 = 1' if (@Cust_Id != '') set @str = @str + ' and Cust_Id = ''' + @Cust_Id + '''' if (@Name != '') set @str = @str + ' and Name like ''' + @Name + '%''' if (@City != '') set @str = @str + ' and City like ''' + @City + '%''' exec (@str) Simple query: select [Sno],[Cust_Id],[Name],[City],[Country],[State] from Customer where (@Cust_Id = '' or Cust_Id = @Cust_Id) and (@Name = '' or Name like @Name + '%') and (@City = '' or City like @City + '%') Which one should I prefer (1 or 2) and what are advantages? After going through everyone's suggestion , here is what i finally got. DECLARE @str NVARCHAR(1000) DECLARE @ParametersDefinition NVARCHAR(500) SET @ParametersDefinition = N'@InnerCust_Id varchar(10), @InnerName varchar(30),@InnerCity varchar(30)' SET @str = 'Select [Sno],[Cust_Id],[Name],[City],[Country],[State] from Customer where 1 = 1' IF(@Cust_Id != '') SET @str = @str + ' and Cust_Id = @InnerCust_Id' IF(@Name != '') SET @str = @str + ' and Name like @InnerName' IF(@City != '') SET @str = @str + ' and City like @InnerCity' -- ADD the % symbol for search based upon the LIKE keyword SELECT @Name = @Name + '%', @City = @City+ '%' EXEC sp_executesql @str, @ParametersDefinition, @InnerCust_Id = @Cust_Id, @InnerName = @Name, @InnerCity = @City; References : http://blogs.lessthandot.com/index.php/DataMgmt/DataDesign/changing-exec-to-sp_executesql-doesn-t-p http://msdn.microsoft.com/en-us/library/ms175170.aspx

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  • How to efficiently use LOCK_ESCALATION mssql 2008

    - by Avias
    I'm currently having troubles with frequent deadlocks with a specific user table in MS SQL 2008. Here are some facts about this particular table: Has a large amount of rows (1 to 2 million) All the indexes used on this table only has "use row lock" ticked on its option rows are frequently updated by multiple transactions but are unique (e.g. probably a thousand or more update statements are executed to different unique rows every hour) the table does not use partitions. Upon checking the table on sys.tables, I found that the lock_escalation is set to TABLE I'm very tempted to turn the lock_escalation for this table to DISABLE but I'm not really sure what side effect this would incur. From What I understand, using DISABLE will minimize escalating locks to TABLE level which if combined with the row lock settings of the indexes should theoretically minimize the deadlocks I am encountering.. From what I have read in Determining threshold for lock escalation it seems that locking automatically escalates when a single transaction fetches 5000 rows.. What does a single transaction mean in this sense? A single session/connection getting 5000 rows thru individual update/select statements? Or is it a single sql update/select statement that fetches 5000 or more rows? Any insight is appreciated, btw, n00b DBA here Thanks

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  • Retrieving values from a table in HTML using jQuery?

    - by Mo
    Hi i was just wondering whats the best way to retrieve the following labels and values from this HTMl code using jquery and storing them in to a array or hash map of some sort where i have for e.g "DataSet:" : "prod" or ["Dataset", "Prod"]? <table id="metric_summary"> <tbody> <tr class="editable_metrics"> <td><label>DataSet:</label></td> <td><input name="DataSet" value="prod"></td> </tr> <tr class="editable_metrics"> <td><label>HostGroup:</label></td> <td><input name="HostGroup" value="MONITOR-PORTAL-IAD"></td> </tr> <tr class="editable_metrics"> <td><label>Host:</label></td> <td><input name="Host" value="ALL"></td> </tr> <tr class="editable_metrics"> <td><label>Class:</label></td> <td><input name="Class" value="CPU"></td> </tr> <tr class="editable_metrics"> <td><label>Object:</label></td> <td><input name="Object" value="cpu"></td> </tr> <tr class="editable_metrics"> <td><label>Metric:</label></td> <td><input name="Metric" value="CapacityCPUUtilization"></td> </tr> thanks

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  • How to current snapshot of MySQL Table and store it into CSV file(after creating it) ?

    - by Rachel
    I have large database table, approximately 5GB, now I wan to getCurrentSnapshot of Database using "Select * from MyTableName", am using PDO in PHP to interact with Database. So preparing a query and then executing it // Execute the prepared query $result->execute(); $resultCollection = $result->fetchAll(PDO::FETCH_ASSOC); is not an efficient way as lots of memory is being user for storing into the associative array data which is approximately, 5GB. My final goal is to collect data returned by Select query into an CSV file and put CSV file at an FTP Location from where Client can get it. Other Option I thought was to do: SELECT * INTO OUTFILE "c:/mydata.csv" FIELDS TERMINATED BY ',' OPTIONALLY ENCLOSED BY '"' LINES TERMINATED BY "\n" FROM my_table; But I am not sure if this would work as I have cron that initiates the complete process and we do not have an csv file, so basically for this approach, PHP Scripts will have to create an CSV file. Do a Select query on the database. Store the select query result into the CSV file. What would be the best or efficient way to do this kind of task ? Any Suggestions !!!

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  • Find multiple patterns with a single preg_match_all in PHP

    - by Mark
    Using PHP and preg_match_all I'm trying to get all the HTML content between the following tags (and the tags also): <p>paragraph text</p> don't take this <ul><li>item 1</li><li>item 2</li></ul> don't take this <table><tr><td>table content</td></tr></table> I can get one of them just fine: preg_match_all("(<p>(.*)</p>)siU", $content, $matches, PREG_SET_ORDER); Is there a way to get all the <p></p> <ul></ul> <table></table> content with a single preg_match_all? I need them to come out in the order they were found so I can echo the content and it will make sense. So if I did a preg_match_all on the above content then iterated through the $matches array it would echo: <p>paragraph text</p> <ul><li>item 1</li><li>item 2</li></ul> <table><tr><td>table content</td></tr></table>

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  • Dynamic programming Approach- Knapsack Puzzle

    - by idalsin
    I'm trying to solve the Knapsack problem with the dynamical programming(DP) approach, with Python 3.x. My TA pointed us towards this code for a head start. I've tried to implement it, as below: def take_input(infile): f_open = open(infile, 'r') lines = [] for line in f_open: lines.append(line.strip()) f_open.close() return lines def create_list(jewel_lines): #turns the jewels into a list of lists jewels_list = [] for x in jewel_lines: weight = x.split()[0] value = x.split()[1] jewels_list.append((int(value), int(weight))) jewels_list = sorted(jewels_list, key = lambda x : (-x[0], x[1])) return jewels_list def dynamic_grab(items, max_weight): table = [[0 for weight in range(max_weight+1)] for j in range(len(items)+1)] for j in range(1,len(items)+1): val= items[j-1][0] wt= items[j-1][1] for weight in range(1, max_weight+1): if wt > weight: table[j][weight] = table[j-1][weight] else: table[j][weight] = max(table[j-1][weight],table[j-1][weight-wt] + val) result = [] weight = max_weight for j in range(len(items),0,-1): was_added = table[j][weight] != table[j-1][weight] if was_added: val = items[j-1][0] wt = items[j-1][1] result.append(items[j-1]) weight -= wt return result def totalvalue(comb): #total of a combo of items totwt = totval = 0 for val, wt in comb: totwt += wt totval += val return (totval, -totwt) if totwt <= max_weight else (0,0) #required setup of variables infile = "JT_test1.txt" given_input = take_input(infile) max_weight = int(given_input[0]) given_input.pop(0) jewels_list = create_list(given_input) #test lines print(jewels_list) print(greedy_grab(jewels_list, max_weight)) bagged = dynamic_grab(jewels_list, max_weight) print(totalvalue(bagged)) The sample case is below. It is in the format line[0] = bag_max, line[1:] is in form(weight, value): 575 125 3000 50 100 500 6000 25 30 I'm confused as to the logic of this code in that it returns me a tuple and I'm not sure what the output tuple represents. I've been looking at this for a while and just don't understand what the code is pointing me at. Any help would be appreciated.

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  • How do I show all group headers in Access 2007 reports?

    - by Newbie
    This is a question about Reports in Access 2007. I'm unsure whether the solution will involve any programming, but hopefully someone will be able to help me. I have a report which lists all records from a particular table (call it A), and groups them by their associated record in a related table (call it B). I use the 'group headers' to add the information from table-B into the report. The problem occurs when I filter the records from table-A that are shown in the report. If I filter out all table-A records that relate to a particular record (call it X) in table-B, the report no longer shows the record-X group header. As a possible workaround, I have tried to ensure that I have one empty record in table-A for each of the records in table-B. That way I can specify NOT to filter out these empty records. However, the outcome is ugly one-record-high blank spaces at the start of each group in the report. Does anyone know of an alternative solution?

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  • Adding a hyperlink in a client report definition file (RDLC)

    - by rajbk
    This post shows you how to add a hyperlink to your RDLC report. In a previous post, I showed you how to create an RDLC report. We have been given the requirement to the report we created earlier, the Northwind Product report, to add a column that will contain hyperlinks which are unique per row.  The URLs will be RESTful with the ProductID at the end. Clicking on the URL will take them to a website like so: http://localhost/products/3  where 3 is the primary key of the product row clicked on. To start off, open the RDLC and add a new column to the product table.   Add text to the header (Details) and row (Product Website). Right click on the row (not header) and select “TextBox properties” Select Action – Go to URL. You could hard code a URL here but what we need is a URL that changes based on the ProductID.   Click on the expression button (fx) The expression builder gives you access to several functions and constants including the fields in your dataset. See this reference for more details: Common Expressions for ReportViewer Reports. Add the following expression: = "http://localhost/products/" & Fields!ProductID.Value Click OK to exit the Expression Builder. The report will not render because hyperlinks are disabled by default in the ReportViewer control. To enable it, add the following in your page load event (where rvProducts is the ID of your ReportViewerControl): protected void Page_Load(object sender, EventArgs e) { if (!IsPostBack) { rvProducts.LocalReport.EnableHyperlinks = true; } } We want our links to open in a new window so set the HyperLinkTarget property of the ReportViewer control to “_blank”   We are done adding hyperlinks to our report. Clicking on the links for each product pops open a new windows. The URL has the ProductID added at the end. Enjoy!

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  • ASP.NET 4.0- Html Encoded Expressions

    - by Jalpesh P. Vadgama
    We all know <%=expression%> features in asp.net. We can print any string on page from there. Mostly we are using them in asp.net mvc. Now we have one new features with asp.net 4.0 that we have HTML Encoded Expressions and this prevent Cross scripting attack as we are html encoding them. ASP.NET 4.0 introduces a new expression syntax <%: expression %> which automatically convert string into html encoded. Let’s take an example for that. I have just created an hello word protected method which will return a simple string which contains characters that needed to be HTML Encoded. Below is code for that. protected static string HelloWorld() { return "Hello World!!! returns from function()!!!>>>>>>>>>>>>>>>>>"; } Now let’s use the that hello world in our page html like below. I am going to use both expression to give you exact difference. <form id="form1" runat="server"> <div> <strong><%: HelloWorld()%></strong> </div> <div> <strong><%= HelloWorld()%></strong> </div> </form> Now let’s run the application and you can see in browser both look similar. But when look into page source html in browser like below you can clearly see one is HTML Encoded and another one is not. That’s it.. It’s cool.. Stay tuned for more.. Happy Programming Technorati Tags: ASP.NET 4.0,HTMLEncode,C#4.0

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  • MVVM Project and Item Templates

    - by Timmy Kokke
    Intro This is the first in a series of small articles about what is new in Silverlight 4 and Expression Blend 4. The series is build around a open source demo application SilverAmp which is available on http://SilverAmp.CodePlex.com.   MVVM Project and Item Templates Expression Blend has got a new project template to get started with a Model-View-ViewModel project  easily. The template provides you with a View and a ViewModel bound together. It also adds the ViewModel to the SampleData of your project. It is available for both Silverlight and Wpf. To get going, start a new project in Expression Blend and select Silverlight DataBound Application from the Silverlight project type. In this case I named the project DemoTest1. The solution now contains several folders: SampleData; which contains a data to show in Blend ViewModels; starts with one file, MainViewModel.cs Views; containing MainView.xaml with codebehind used for binding with the MainViewModel class. and your regular App.xaml and MainPage.xaml The MainViewModel class contains a sample property and a sample method. Both the property and the method are used in the MainView control. The MainView control is a regular UserControl and is placed in the MainPage. You can continue on building your applicaition by adding your own properties and methods to the ViewModel and adding controls to the View. Adding Views with ViewModels is very easy too. The guys at Microsoft where nice enough to add a new Item template too: a UserControl with ViewModel. If you add this new item to the root of your solution it will add the .xaml file to the views folder and a .cs file to the ViewModels folder. Conclusion The databound Application project type is a great to get your MVVM based project started. It also functions a great source of information about how to connect it all together.   Technorati Tags: Silverlight,Wpf,Expression Blend,MVVM

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  • What is the best book on Silverlight 4?

    - by mbcrump
    Silverlight/Expression 4 Books! I recently stumbled upon a post asking, “What is the best book on Silverlight 4?” In the age of the internet, it can be hard for anyone searching for a good book to actually find it. I have read a few Silverlight 4/Expression books in 2010 and decided to post the “best of” collection. Instead of reading multiple books, you can cut your list down to whatever category that you fit in. With Silverlight 5 coming soon, now is the time to get up to speed with what Silverlight 4 can offer. Be sure to read the full review at the bottom of each section. For the “Beginner” Silverlight Developer: Both of these books contains very simple applications and will get you started very fast. and Book Review: Microsoft Silverlight 4 Step by Step For the guy/gal that wants to “Master” Expression Blend 4: This is a hands-on kind of book. Victor get you started early on with some sample application and quickly deep dives into Storyboard and other Animations. If you want to learn Blend 4 then this is the place to start. Book Review: Foundation Expression Blend 4 by Victor Gaudioso If you are aiming to learn more about the Business side of Silverlight then check out the following two books: and Finally, For the Silverlight 4 guy/gal that wants to “Master” Silverlight 4, it really boils down to the following two books: and   Book Review: Silverlight 4 Unleashed by Laurent Bugnion Book Review: Silverlight 4 in Action by Pete Brown I can’t describe how much that I’ve actually learned from both of these books. I would also recommend you read these books if you are preparing for your Silverlight 4 Certification. For a complete list of all Silverlight 4 books then check out http://www.silverlight.net/learn/books/ and don’t forget to subscribe to my blog.  Subscribe to my feed CodeProject

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  • Dynamic filter expressions in an OpenAccess LINQ query

    We had some support questions recently where our customers had the need to combine multiple smaller predicate expressions with either an OR or an AND  logical operators (these will be the || and && operators if you are using C#). And because the code from the answer that we sent to these customers is very interesting, and can easily be refactorred into something reusable, we decided to write this blog post. The key thing that one must know is that if you want your predicate to be translated by OpenAccess ORM to SQL and executed on the server you must have a LINQ Expression that is not compiled. So, let’s say that you have these smaller predicate expressions: Expression<Func<Customer, bool>> filter1 = c => c.City.StartsWith("S");Expression<Func<Customer, bool>> filter2 = c => c.City.StartsWith("M");Expression<Func<Customer, bool>> filter3 = c => c.ContactTitle == "Owner"; And ...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • heimdal kerberos in openldap issue

    - by Brian
    I think I posted this on the wrong 'sister site', so here it is. I'm having a bit of trouble getting Kerberos (Heimdal version) to work nicely with OpenLDAP. The kerberos database is being stored in LDAP itself. The KDC uses SASL EXTERNAL authentication as root to access the container ou. I created the database in LDAP fine using kadmin -l, but it won't let me use kadmin without the -l flag: root@rds0:~# kadmin -l kadmin> list * krbtgt/REALM kadmin/changepw kadmin/admin changepw/kerberos kadmin/hprop WELLKNOWN/ANONYMOUS WELLKNOWN/org.h5l.fast-cookie@WELLKNOWN:ORG.H5L default brian.empson brian.empson/admin host/rds0.example.net ldap/rds0.example.net host/localhost kadmin> exit root@rds0:~# kadmin kadmin> list * brian.empson/admin@REALM's Password: <----- With right password kadmin: kadm5_get_principals: Key table entry not found kadmin> list * brian.empson/admin@REALM's Password: <------ With wrong password kadmin: kadm5_get_principals: Already tried ENC-TS-info, looping kadmin> I can get tickets without a problem: root@rds0:~# klist Credentials cache: FILE:/tmp/krb5cc_0 Principal: brian.empson@REALM Issued Expires Principal Nov 11 14:14:40 2012 Nov 12 00:14:37 2012 krbtgt/REALM@REALM Nov 11 14:40:35 2012 Nov 12 00:14:37 2012 ldap/rds0.example.net@REALM But I can't seem to change my own password without kadmin -l: root@rds0:~# kpasswd brian.empson@REALM's Password: <---- Right password New password: Verify password - New password: Auth error : Authentication failed root@rds0:~# kpasswd brian.empson@REALM's Password: <---- Wrong password kpasswd: krb5_get_init_creds: Already tried ENC-TS-info, looping kadmin's logs are not helpful at all: 2012-11-11T13:48:33 krb5_recvauth: Key table entry not found 2012-11-11T13:51:18 krb5_recvauth: Key table entry not found 2012-11-11T13:53:02 krb5_recvauth: Key table entry not found 2012-11-11T14:16:34 krb5_recvauth: Key table entry not found 2012-11-11T14:20:24 krb5_recvauth: Key table entry not found 2012-11-11T14:20:44 krb5_recvauth: Key table entry not found 2012-11-11T14:21:29 krb5_recvauth: Key table entry not found 2012-11-11T14:21:46 krb5_recvauth: Key table entry not found 2012-11-11T14:23:09 krb5_recvauth: Key table entry not found 2012-11-11T14:45:39 krb5_recvauth: Key table entry not found The KDC reports that both accounts succeed in authenticating: 2012-11-11T14:48:03 AS-REQ brian.empson@REALM from IPv4:192.168.72.10 for kadmin/changepw@REALM 2012-11-11T14:48:03 Client sent patypes: REQ-ENC-PA-REP 2012-11-11T14:48:03 Looking for PK-INIT(ietf) pa-data -- brian.empson@REALM 2012-11-11T14:48:03 Looking for PK-INIT(win2k) pa-data -- brian.empson@REALM 2012-11-11T14:48:03 Looking for ENC-TS pa-data -- brian.empson@REALM 2012-11-11T14:48:03 Need to use PA-ENC-TIMESTAMP/PA-PK-AS-REQ 2012-11-11T14:48:03 sending 294 bytes to IPv4:192.168.72.10 2012-11-11T14:48:03 AS-REQ brian.empson@REALM from IPv4:192.168.72.10 for kadmin/changepw@REALM 2012-11-11T14:48:03 Client sent patypes: ENC-TS, REQ-ENC-PA-REP 2012-11-11T14:48:03 Looking for PK-INIT(ietf) pa-data -- brian.empson@REALM 2012-11-11T14:48:03 Looking for PK-INIT(win2k) pa-data -- brian.empson@REALM 2012-11-11T14:48:03 Looking for ENC-TS pa-data -- brian.empson@REALM 2012-11-11T14:48:03 ENC-TS Pre-authentication succeeded -- brian.empson@REALM using aes256-cts-hmac-sha1-96 2012-11-11T14:48:03 ENC-TS pre-authentication succeeded -- brian.empson@REALM 2012-11-11T14:48:03 AS-REQ authtime: 2012-11-11T14:48:03 starttime: unset endtime: 2012-11-11T14:53:00 renew till: unset 2012-11-11T14:48:03 Client supported enctypes: aes256-cts-hmac-sha1-96, aes128-cts-hmac-sha1-96, des3-cbc-sha1, arcfour-hmac-md5, using aes256-cts-hmac-sha1-96/aes256-cts-hmac-sha1-96 2012-11-11T14:48:03 sending 704 bytes to IPv4:192.168.72.10 2012-11-11T14:45:39 AS-REQ brian.empson/admin@REALM from IPv4:192.168.72.10 for kadmin/admin@REALM 2012-11-11T14:45:39 Client sent patypes: REQ-ENC-PA-REP 2012-11-11T14:45:39 Looking for PK-INIT(ietf) pa-data -- brian.empson/admin@REALM 2012-11-11T14:45:39 Looking for PK-INIT(win2k) pa-data -- brian.empson/admin@REALM 2012-11-11T14:45:39 Looking for ENC-TS pa-data -- brian.empson/admin@REALM 2012-11-11T14:45:39 Need to use PA-ENC-TIMESTAMP/PA-PK-AS-REQ 2012-11-11T14:45:39 sending 303 bytes to IPv4:192.168.72.10 2012-11-11T14:45:39 AS-REQ brian.empson/admin@REALM from IPv4:192.168.72.10 for kadmin/admin@REALM 2012-11-11T14:45:39 Client sent patypes: ENC-TS, REQ-ENC-PA-REP 2012-11-11T14:45:39 Looking for PK-INIT(ietf) pa-data -- brian.empson/admin@REALM 2012-11-11T14:45:39 Looking for PK-INIT(win2k) pa-data -- brian.empson/admin@REALM 2012-11-11T14:45:39 Looking for ENC-TS pa-data -- brian.empson/admin@REALM 2012-11-11T14:45:39 ENC-TS Pre-authentication succeeded -- brian.empson/admin@REALM using aes256-cts-hmac-sha1-96 2012-11-11T14:45:39 ENC-TS pre-authentication succeeded -- brian.empson/admin@REALM 2012-11-11T14:45:39 AS-REQ authtime: 2012-11-11T14:45:39 starttime: unset endtime: 2012-11-11T15:45:39 renew till: unset 2012-11-11T14:45:39 Client supported enctypes: aes256-cts-hmac-sha1-96, aes128-cts-hmac-sha1-96, des3-cbc-sha1, arcfour-hmac-md5, using aes256-cts-hmac-sha1-96/aes256-cts-hmac-sha1-96 2012-11-11T14:45:39 sending 717 bytes to IPv4:192.168.72.10 I wish I had more detailed logging messages, running kadmind in debug mode seems to almost work but it just kicks me back to the shell when I type in the correct password. GSSAPI via LDAP doesn't work either, but I suspect it's because some parts of kerberos aren't working either: root@rds0:~# ldapsearch -Y GSSAPI -H ldaps:/// -b "o=mybase" o=mybase SASL/GSSAPI authentication started ldap_sasl_interactive_bind_s: Other (e.g., implementation specific) error (80) additional info: SASL(-1): generic failure: GSSAPI Error: Unspecified GSS failure. Minor code may provide more information () root@rds0:~# ldapsearch -Y EXTERNAL -H ldapi:/// -b "o=mybase" o=mybase SASL/EXTERNAL authentication started SASL username: gidNumber=0+uidNumber=0,cn=peercred,cn=external,cn=auth SASL SSF: 0 # extended LDIF <snip> Would anyone be able to point me in the right direction?

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  • NHibernate Conventions

    - by Ricardo Peres
    Introduction It seems that nowadays everyone loves conventions! Not the ones that you go to, but the ones that you use, that is! It just happens that NHibernate also supports conventions, and we’ll see exactly how. Conventions in NHibernate are supported in two ways: Naming of tables and columns when not explicitly indicated in the mappings; Full domain mapping. Naming of Tables and Columns Since always NHibernate has supported the concept of a naming strategy. A naming strategy in NHibernate converts class and property names to table and column names and vice-versa, when a name is not explicitly supplied. In concrete, it must be a realization of the NHibernate.Cfg.INamingStrategy interface, of which NHibernate includes two implementations: DefaultNamingStrategy: the default implementation, where each column and table are mapped to identically named properties and classes, for example, “MyEntity” will translate to “MyEntity”; ImprovedNamingStrategy: underscores (_) are used to separate Pascal-cased fragments, for example, entity “MyEntity” will be mapped to a “my_entity” table. The naming strategy can be defined at configuration level (the Configuration instance) by calling the SetNamingStrategy method: 1: cfg.SetNamingStrategy(ImprovedNamingStrategy.Instance); Both the DefaultNamingStrategy and the ImprovedNamingStrategy classes offer singleton instances in the form of Instance static fields. DefaultNamingStrategy is the one NHibernate uses, if you don’t specify one. Domain Mapping In mapping by code, we have the choice of relying on conventions to do the mapping automatically. This means a class will inspect our classes and decide how they will relate to the database objects. The class that handles conventions is NHibernate.Mapping.ByCode.ConventionModelMapper, a specialization of the base by code mapper, NHibernate.Mapping.ByCode.ModelMapper. The ModelMapper relies on an internal SimpleModelInspector to help it decide what and how to map, but the mapper lets you override its decisions.  You apply code conventions like this: 1: //pick the types that you want to map 2: IEnumerable<Type> types = Assembly.GetExecutingAssembly().GetExportedTypes(); 3:  4: //conventions based mapper 5: ConventionModelMapper mapper = new ConventionModelMapper(); 6:  7: HbmMapping mapping = mapper.CompileMappingFor(types); 8:  9: //the one and only configuration instance 10: Configuration cfg = ...; 11: cfg.AddMapping(mapping); This is a very simple example, it lacks, at least, the id generation strategy, which you can add by adding an event handler like this: 1: mapper.BeforeMapClass += (IModelInspector modelInspector, Type type, IClassAttributesMapper classCustomizer) => 2: { 3: classCustomizer.Id(x => 4: { 5: //set the hilo generator 6: x.Generator(Generators.HighLow); 7: }); 8: }; The mapper will fire events like this whenever it needs to get information about what to do. And basically this is all it takes to automatically map your domain! It will correctly configure many-to-one and one-to-many relations, choosing bags or sets depending on your collections, will get the table and column names from the naming strategy we saw earlier and will apply the usual defaults to all properties, such as laziness and fetch mode. However, there is at least one thing missing: many-to-many relations. The conventional mapper doesn’t know how to find and configure them, which is a pity, but, alas, not difficult to overcome. To start, for my projects, I have this rule: each entity exposes a public property of type ISet<T> where T is, of course, the type of the other endpoint entity. Extensible as it is, NHibernate lets me implement this very easily: 1: mapper.IsOneToMany((MemberInfo member, Boolean isLikely) => 2: { 3: Type sourceType = member.DeclaringType; 4: Type destinationType = member.GetMemberFromDeclaringType().GetPropertyOrFieldType(); 5:  6: //check if the property is of a generic collection type 7: if ((destinationType.IsGenericCollection() == true) && (destinationType.GetGenericArguments().Length == 1)) 8: { 9: Type destinationEntityType = destinationType.GetGenericArguments().Single(); 10:  11: //check if the type of the generic collection property is an entity 12: if (mapper.ModelInspector.IsEntity(destinationEntityType) == true) 13: { 14: //check if there is an equivalent property on the target type that is also a generic collection and points to this entity 15: PropertyInfo collectionInDestinationType = destinationEntityType.GetProperties().Where(x => (x.PropertyType.IsGenericCollection() == true) && (x.PropertyType.GetGenericArguments().Length == 1) && (x.PropertyType.GetGenericArguments().Single() == sourceType)).SingleOrDefault(); 16:  17: if (collectionInDestinationType != null) 18: { 19: return (false); 20: } 21: } 22: } 23:  24: return (true); 25: }); 26:  27: mapper.IsManyToMany((MemberInfo member, Boolean isLikely) => 28: { 29: //a relation is many to many if it isn't one to many 30: Boolean isOneToMany = mapper.ModelInspector.IsOneToMany(member); 31: return (!isOneToMany); 32: }); 33:  34: mapper.BeforeMapManyToMany += (IModelInspector modelInspector, PropertyPath member, IManyToManyMapper collectionRelationManyToManyCustomizer) => 35: { 36: Type destinationEntityType = member.LocalMember.GetPropertyOrFieldType().GetGenericArguments().First(); 37: //set the mapping table column names from each source entity name plus the _Id sufix 38: collectionRelationManyToManyCustomizer.Column(destinationEntityType.Name + "_Id"); 39: }; 40:  41: mapper.BeforeMapSet += (IModelInspector modelInspector, PropertyPath member, ISetPropertiesMapper propertyCustomizer) => 42: { 43: if (modelInspector.IsManyToMany(member.LocalMember) == true) 44: { 45: propertyCustomizer.Key(x => x.Column(member.LocalMember.DeclaringType.Name + "_Id")); 46:  47: Type sourceType = member.LocalMember.DeclaringType; 48: Type destinationType = member.LocalMember.GetPropertyOrFieldType().GetGenericArguments().First(); 49: IEnumerable<String> names = new Type[] { sourceType, destinationType }.Select(x => x.Name).OrderBy(x => x); 50:  51: //set inverse on the relation of the alphabetically first entity name 52: propertyCustomizer.Inverse(sourceType.Name == names.First()); 53: //set mapping table name from the entity names in alphabetical order 54: propertyCustomizer.Table(String.Join("_", names)); 55: } 56: }; We have to understand how the conventions mapper thinks: For each collection of entities found, it will ask the mapper if it is a one-to-many; in our case, if the collection is a generic one that has an entity as its generic parameter, and the generic parameter type has a similar collection, then it is not a one-to-many; Next, the mapper will ask if the collection that it now knows is not a one-to-many is a many-to-many; Before a set is mapped, if it corresponds to a many-to-many, we set its mapping table. Now, this is tricky: because we have no way to maintain state, we sort the names of the two endpoint entities and we combine them with a “_”; for the first alphabetical entity, we set its relation to inverse – remember, on a many-to-many relation, only one endpoint must be marked as inverse; finally, we set the column name as the name of the entity with an “_Id” suffix; Before the many-to-many relation is processed, we set the column name as the name of the other endpoint entity with the “_Id” suffix, as we did for the set. And that’s it. With these rules, NHibernate will now happily find and configure many-to-many relations, as well as all the others. You can wrap this in a new conventions mapper class, so that it is more easily reusable: 1: public class ManyToManyConventionModelMapper : ConventionModelMapper 2: { 3: public ManyToManyConventionModelMapper() 4: { 5: base.IsOneToMany((MemberInfo member, Boolean isLikely) => 6: { 7: return (this.IsOneToMany(member, isLikely)); 8: }); 9:  10: base.IsManyToMany((MemberInfo member, Boolean isLikely) => 11: { 12: return (this.IsManyToMany(member, isLikely)); 13: }); 14:  15: base.BeforeMapManyToMany += this.BeforeMapManyToMany; 16: base.BeforeMapSet += this.BeforeMapSet; 17: } 18:  19: protected virtual Boolean IsManyToMany(MemberInfo member, Boolean isLikely) 20: { 21: //a relation is many to many if it isn't one to many 22: Boolean isOneToMany = this.ModelInspector.IsOneToMany(member); 23: return (!isOneToMany); 24: } 25:  26: protected virtual Boolean IsOneToMany(MemberInfo member, Boolean isLikely) 27: { 28: Type sourceType = member.DeclaringType; 29: Type destinationType = member.GetMemberFromDeclaringType().GetPropertyOrFieldType(); 30:  31: //check if the property is of a generic collection type 32: if ((destinationType.IsGenericCollection() == true) && (destinationType.GetGenericArguments().Length == 1)) 33: { 34: Type destinationEntityType = destinationType.GetGenericArguments().Single(); 35:  36: //check if the type of the generic collection property is an entity 37: if (this.ModelInspector.IsEntity(destinationEntityType) == true) 38: { 39: //check if there is an equivalent property on the target type that is also a generic collection and points to this entity 40: PropertyInfo collectionInDestinationType = destinationEntityType.GetProperties().Where(x => (x.PropertyType.IsGenericCollection() == true) && (x.PropertyType.GetGenericArguments().Length == 1) && (x.PropertyType.GetGenericArguments().Single() == sourceType)).SingleOrDefault(); 41:  42: if (collectionInDestinationType != null) 43: { 44: return (false); 45: } 46: } 47: } 48:  49: return (true); 50: } 51:  52: protected virtual new void BeforeMapManyToMany(IModelInspector modelInspector, PropertyPath member, IManyToManyMapper collectionRelationManyToManyCustomizer) 53: { 54: Type destinationEntityType = member.LocalMember.GetPropertyOrFieldType().GetGenericArguments().First(); 55: //set the mapping table column names from each source entity name plus the _Id sufix 56: collectionRelationManyToManyCustomizer.Column(destinationEntityType.Name + "_Id"); 57: } 58:  59: protected virtual new void BeforeMapSet(IModelInspector modelInspector, PropertyPath member, ISetPropertiesMapper propertyCustomizer) 60: { 61: if (modelInspector.IsManyToMany(member.LocalMember) == true) 62: { 63: propertyCustomizer.Key(x => x.Column(member.LocalMember.DeclaringType.Name + "_Id")); 64:  65: Type sourceType = member.LocalMember.DeclaringType; 66: Type destinationType = member.LocalMember.GetPropertyOrFieldType().GetGenericArguments().First(); 67: IEnumerable<String> names = new Type[] { sourceType, destinationType }.Select(x => x.Name).OrderBy(x => x); 68:  69: //set inverse on the relation of the alphabetically first entity name 70: propertyCustomizer.Inverse(sourceType.Name == names.First()); 71: //set mapping table name from the entity names in alphabetical order 72: propertyCustomizer.Table(String.Join("_", names)); 73: } 74: } 75: } Conclusion Of course, there is much more to mapping than this, I suggest you look at all the events and functions offered by the ModelMapper to see where you can hook for making it behave the way you want. If you need any help, just let me know!

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  • VLOOKUP in Excel, part 2: Using VLOOKUP without a database

    - by Mark Virtue
    In a recent article, we introduced the Excel function called VLOOKUP and explained how it could be used to retrieve information from a database into a cell in a local worksheet.  In that article we mentioned that there were two uses for VLOOKUP, and only one of them dealt with querying databases.  In this article, the second and final in the VLOOKUP series, we examine this other, lesser known use for the VLOOKUP function. If you haven’t already done so, please read the first VLOOKUP article – this article will assume that many of the concepts explained in that article are already known to the reader. When working with databases, VLOOKUP is passed a “unique identifier” that serves to identify which data record we wish to find in the database (e.g. a product code or customer ID).  This unique identifier must exist in the database, otherwise VLOOKUP returns us an error.  In this article, we will examine a way of using VLOOKUP where the identifier doesn’t need to exist in the database at all.  It’s almost as if VLOOKUP can adopt a “near enough is good enough” approach to returning the data we’re looking for.  In certain circumstances, this is exactly what we need. We will illustrate this article with a real-world example – that of calculating the commissions that are generated on a set of sales figures.  We will start with a very simple scenario, and then progressively make it more complex, until the only rational solution to the problem is to use VLOOKUP.  The initial scenario in our fictitious company works like this:  If a salesperson creates more than $30,000 worth of sales in a given year, the commission they earn on those sales is 30%.  Otherwise their commission is only 20%.  So far this is a pretty simple worksheet: To use this worksheet, the salesperson enters their sales figures in cell B1, and the formula in cell B2 calculates the correct commission rate they are entitled to receive, which is used in cell B3 to calculate the total commission that the salesperson is owed (which is a simple multiplication of B1 and B2). The cell B2 contains the only interesting part of this worksheet – the formula for deciding which commission rate to use: the one below the threshold of $30,000, or the one above the threshold.  This formula makes use of the Excel function called IF.  For those readers that are not familiar with IF, it works like this: IF(condition,value if true,value if false) Where the condition is an expression that evaluates to either true or false.  In the example above, the condition is the expression B1<B5, which can be read as “Is B1 less than B5?”, or, put another way, “Are the total sales less than the threshold”.  If the answer to this question is “yes” (true), then we use the value if true parameter of the function, namely B6 in this case – the commission rate if the sales total was below the threshold.  If the answer to the question is “no” (false), then we use the value if false parameter of the function, namely B7 in this case – the commission rate if the sales total was above the threshold. As you can see, using a sales total of $20,000 gives us a commission rate of 20% in cell B2.  If we enter a value of $40,000, we get a different commission rate: So our spreadsheet is working. Let’s make it more complex.  Let’s introduce a second threshold:  If the salesperson earns more than $40,000, then their commission rate increases to 40%: Easy enough to understand in the real world, but in cell B2 our formula is getting more complex.  If you look closely at the formula, you’ll see that the third parameter of the original IF function (the value if false) is now an entire IF function in its own right.  This is called a nested function (a function within a function).  It’s perfectly valid in Excel (it even works!), but it’s harder to read and understand. We’re not going to go into the nuts and bolts of how and why this works, nor will we examine the nuances of nested functions.  This is a tutorial on VLOOKUP, not on Excel in general. Anyway, it gets worse!  What about when we decide that if they earn more than $50,000 then they’re entitled to 50% commission, and if they earn more than $60,000 then they’re entitled to 60% commission? Now the formula in cell B2, while correct, has become virtually unreadable.  No-one should have to write formulae where the functions are nested four levels deep!  Surely there must be a simpler way? There certainly is.  VLOOKUP to the rescue! Let’s redesign the worksheet a bit.  We’ll keep all the same figures, but organize it in a new way, a more tabular way: Take a moment and verify for yourself that the new Rate Table works exactly the same as the series of thresholds above. Conceptually, what we’re about to do is use VLOOKUP to look up the salesperson’s sales total (from B1) in the rate table and return to us the corresponding commission rate.  Note that the salesperson may have indeed created sales that are not one of the five values in the rate table ($0, $30,000, $40,000, $50,000 or $60,000).  They may have created sales of $34,988.  It’s important to note that $34,988 does not appear in the rate table.  Let’s see if VLOOKUP can solve our problem anyway… We select cell B2 (the location we want to put our formula), and then insert the VLOOKUP function from the Formulas tab: The Function Arguments box for VLOOKUP appears.  We fill in the arguments (parameters) one by one, starting with the Lookup_value, which is, in this case, the sales total from cell B1.  We place the cursor in the Lookup_value field and then click once on cell B1: Next we need to specify to VLOOKUP what table to lookup this data in.  In this example, it’s the rate table, of course.  We place the cursor in the Table_array field, and then highlight the entire rate table – excluding the headings: Next we must specify which column in the table contains the information we want our formula to return to us.  In this case we want the commission rate, which is found in the second column in the table, so we therefore enter a 2 into the Col_index_num field: Finally we enter a value in the Range_lookup field. Important:  It is the use of this field that differentiates the two ways of using VLOOKUP.  To use VLOOKUP with a database, this final parameter, Range_lookup, must always be set to FALSE, but with this other use of VLOOKUP, we must either leave it blank or enter a value of TRUE.  When using VLOOKUP, it is vital that you make the correct choice for this final parameter. To be explicit, we will enter a value of true in the Range_lookup field.  It would also be fine to leave it blank, as this is the default value: We have completed all the parameters.  We now click the OK button, and Excel builds our VLOOKUP formula for us: If we experiment with a few different sales total amounts, we can satisfy ourselves that the formula is working. Conclusion In the “database” version of VLOOKUP, where the Range_lookup parameter is FALSE, the value passed in the first parameter (Lookup_value) must be present in the database.  In other words, we’re looking for an exact match. But in this other use of VLOOKUP, we are not necessarily looking for an exact match.  In this case, “near enough is good enough”.  But what do we mean by “near enough”?  Let’s use an example:  When searching for a commission rate on a sales total of $34,988, our VLOOKUP formula will return us a value of 30%, which is the correct answer.  Why did it choose the row in the table containing 30% ?  What, in fact, does “near enough” mean in this case?  Let’s be precise: When Range_lookup is set to TRUE (or omitted), VLOOKUP will look in column 1 and match the highest value that is not greater than the Lookup_value parameter. It’s also important to note that for this system to work, the table must be sorted in ascending order on column 1! If you would like to practice with VLOOKUP, the sample file illustrated in this article can be downloaded from here. Similar Articles Productive Geek Tips Using VLOOKUP in ExcelImport Microsoft Access Data Into ExcelImport an Access Database into ExcelCopy a Group of Cells in Excel 2007 to the Clipboard as an ImageShare Access Data with Excel in Office 2010 TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips DVDFab 6 Revo Uninstaller Pro Registry Mechanic 9 for Windows PC Tools Internet Security Suite 2010 Quickly Schedule Meetings With NeedtoMeet Share Flickr Photos On Facebook Automatically Are You Blocked On Gtalk? Find out Discover Latest Android Apps On AppBrain The Ultimate Guide For YouTube Lovers Will it Blend? iPad Edition

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