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• How much does Website Development cost nowadays?

  - by Andreas Grech

  I am thinking of setting up my own freelance business but coming from a workplace that offers a particular service to huge clients, I do not know what are the current charges for websites are nowadays. I know that as technology just keeps changing and changing (most of the time, for the better...), the amount you charge for a single website is constantly differing. Like for example, I don't think static websites (with just static html pages) are that expensive today, no? (as i said, I might be mistaken since I haven't really touched on this freelance industry yet) So, freelance web-developers out there, can you give me estimates on how much you charge for your clients? Some examples of websites that I want to know an approx charge: ~10 static html pages ~10 dhtml pages (with maybe a flasy menu on the top/side) Database driven websites with a standard CMS (be it the one you developed, or an existing one) Database driven but with a custom-built cms for the particular client Using an existing template for a design Starting the design from scratch etc... I know that the normally clients don't really care about the technologies used to construct their websites, but do you charge differently according to which technology you use to build the website with?; as in, is the technology a factor when setting the price? ...being ASP.Net, PHP, Ruby On Rails etc... Also, how do you go on about charging your clients for your services? What are the major factors that you consider when setting a price tag for a website to a client ? And better yet, how do you even find prospective clients? <= [or should I leave this question for a different post?] Btw, in your post, also mention some numbers (in cash values, be it in USD, GBP, EUR or anything) because I want to be able to take calculate some averages from this post when some answers stack up

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• Why does Perl's DBI complain about "failed: ERROR OCIEnvNlsCreate" when I try to connect to Oracle 1

  - by John

  I am getting the following error connecting to an Oracle 11g database using a simple Perl script: failed: ERROR OCIEnvNlsCreate. Check ORACLE_HOME (Linux) env var or PATH (Windows) and or NLS settings, permissions, etc. at The script is as follows: #!/usr/local/bin/perl use strict; use DBI; if ($#ARGV < 3) { print "Usage: perl testDbAccess.pl dataBaseUser dataBasePassword SID dataBasePort\n"; exit 0; } my ($user, $pwd, $sid, $port) = @ARGV; my $host = `hostname`; my $dbh; my $sth; my $dbname = "dbi:Oracle:HOST=$host;SID=$sid;PORT=$port"; openDbConnection(); closeDbConnection(); sub openDbConnection() { $dbh = DBI->connect ($dbname, $user ,$pwd , { RaiseError => 1}) || die "Database connection not made: $DBI::errstr"; } sub closeDbConnection() { #$sth->finish(); $dbh->disconnect(); } Anyone seen this problem before?

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• How can I map stored procedure result into a custom class with linq-to-sql?

  - by Remnant

  I have a stored procedure that returns a result set (4 columns x n Rows). The data is based on multiple tables within my database and provides a summary for each department within a corporate. Here is sample: usp_GetDepartmentSummary DeptName EmployeeCount Male Female HR 12 5 7 etc... I am using linq-to-sql to retrieve data from my database (nb - have to use sproc as it is something I have inherited). I would like to call the above sproc and map into a department class: public class Department { public string DeptName {get; set;} public int EmployeeCount {get; set;} public int MaleCount {get; set;} public int FemaleCount {get; set;} } In VS2008, I can drag and drop my sproc onto the methods pane of the linq-to-sql designer. When I examine the designer.cs the return type for this sproc is defined as: ISingleResult<usp_GetDepartmentSummaryResult> What I would like to do is amend this somehow so that it returns a Department type so that I can pass the results of the sproc as a strongly typed view: <% foreach (var dept in Model) { %> <ul> <li class="deptname"><%= dept.DeptName %></li> <li class="deptname"><%= dept.EmployeeCount %></li> etc... Any ideas how to achieve this? NB - I have tried amending the designer.cs and dbml xml file directly but with limited success. I admit to being a little out of my depth when it comes to updating those files directly and I am not sure it is best practice? Would be good to get some diretion. Thanks much

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• ASP.NET retrieve Average CPU Usage

  - by Sam

  Last night I did a load test on a site. I found that one of my shared caches is a bottleneck. I'm using a ReaderWriterLockSlim to control the updates of the data. Unfortunately at one point there are ~200 requests trying to update the data at approximately the same time. This also coincided with CPU usage spikes. The data being updated is in the ASP.NET Cache. What I'd like to do is if the CPU usage is around 75%, I'd like to just skip the cache and hit the database on another machine. My problem is that I don't know how expensive it is to create a new performance counter to check the cpu usage. Also, if I would probably like the average cpu usage over the last 2 or 3 seconds. However, I can't sit there and calculate the cpu time as that would take longer than it's taking to update the cache currently. Is there an easy way to get the average CPU usage? Are there any drawbacks to this? I'm also considering totaling the wait count for the lock and then at a certain threshold switch over to the database. The concern I had with this approach would be that changing hardware might allow more locks with less of a strain on the system. And also finding the right balance for the threshold would be cumbersome and it doesn't take into account any other load on the machine. But it's a simple approach, and simple is 99% of the time better.

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• Family Tree :- myheritage.com

  - by Nitesh Panchal

  Hello, The other day i just accidently visited the site myheritage.com. I was just wondering, how they must have created one? Can anybody tell me what can be their database design? and if possible, algorithm that we can use to generate such a tree? Generating simple binary tree is very easy using recursion. But if you have a look at the site(if you have time please make account on it and add few nodes to feel) when we add son to a father, it's mother is automatically added(if you don't add explicitly). Mother's family tree is also generated side by side and many such fancy things are happening. In a simple binary tree we have a root node and then many nodes below it. Thus we cannot show wife and husband in the tree and then show a line from wife and husband to child. In spare time, can anybody discuss what can be it's database design and the recursive algorithm that we can follow to generate it? I hope i am not asking too much from you :).

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• First site going live real soon. Last minute questions

  - by user156814

  I am really close to finishing up on a project that I've been working on. I have done websites before, but never on my own and never a site that involved user generated data. I have been reading up on things that should be considered before you go live and I have some questions. 1) Staging... (Deploying updates without affecting users). I'm not really sure what this would entail, since I'm sure that any type of update would affect users in some way. Does this mean some type of temporary downtime for every update? can somebody please explain this and a solution to this as well. 2) Limits... I'm using the Kohana framework and I'm using the Auth module for logging users in. I was wondering if this already has some type of limit (on login attempts) built in, and if not, what would be the best way to implement this. (save attempts in database, cookie, etc.). If this is not whats meant by limits, can somebody elaborate. 3) Caching... Like I said, this is my first site built around user content. Considering that, should I cache it? 4) Back Ups... How often should I backup my (MySQL) database, and how should I back it up (MySQL export?). The site is currently up, yet not finished, if anybody wants to look at it and see if something pops out to you that should be looked at/fixed. Clashing Thoughts. If there is anything else I overlooked, thats not already in the list linked to above, please let me know. Thanks.

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• Spring MVC + Hibernate encoding problem

  - by Bar

  I work on Spring MVC + Hibernate application, use MySQL (ver. 5.0.51a) with the InnoDB engine. The problem appears when I am sending a form with cyrillic characters. As the result, database contains senseless chars in unknown encoding. All the JSP pages, database (+ tables and fields) created using UTF-8. Hibernate config also contains property which sets encoding to UTF-8. I had solved this by creating filter which encodes request content with UTF-8. Exemplary code: … encoding = "UTF-8"; request.setCharacterEncoding(encoding); chain.doFilter(request, response); … But it visibly slows down the app. The interesting thing is that executing insert query directly from the app (i.e. running from Eclipse as Java Application) works perfect. Any suggestions are welcome. TIA, Michael.

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• Windows service threading call to WCF service

  - by Sam Brinsted

  Hi, I have a windows service that is reading data from a database and then submitting it to a WCF serivce. Once that has finished it is stamping a processed date on the original record. Trouble I am currently having is to do with threading. The call to the WCF serivce is relatively long and I want to have a number of concurrent calls to the service to help improve the throughput of the windows service. Currently I have a submitToService method on a new worker class. Upon reading a new row from the database I am creating a new thread which is calling this method. This obviously isn't too good as the number of threads quickly shoots up and overburdens the WCF service. I have put a thread.sleep in the submit method and am sure to call System.Threading.Thread.CurrentThread.Abort(); after the submission has finished. However, I don't seem to see the number of threads go down. How can I just have a fixed number of threads that can be used in the windows service? I did think about using a thread pool but read somewhere that wasn't a good choice for a windows service. Thanks very much.

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• Doctrine Default Primary Key Problem (Again)

  - by 01010011

  Hi, Should I change all of my uniquely-named MySQL database primary keys to 'id' to avoid getting errors related to Doctrine's default primary key set in the plugin 'doctrine_pi.php'? To further elaborate, I am getting the following reoccurring error, this time after trying to login to my login page: SQLSTATE[42S22]: Column not found: 1054 Unknown column 'u.book_id' in 'field list'' in... I suspect the problem resides at a MySQL table used for my login, of which has a primary key called id Marc B originally solved an identical problem for me in this post http://stackoverflow.com/questions/2702229/doctrine-codeigniter-mysql-crud-errors when I had the same problem with a different table within the same database. Following his suggestion, I changed the default primary key located at system/application/plugins/doctrine_pi.php from 'id' to 'book_id': <?php // system/application/plugins/doctrine_pi.php ... // set the default primary key to be named 'id', integer, 4 bytes Doctrine_Manager::getInstance()->setAttribute( Doctrine::ATTR_DEFAULT_IDENTIFIER_OPTIONS, array('name' => 'book_id', 'type' => 'integer', 'length' => 4)); and that solved my previous problem. However, my login page stopped working. So what is the safe thing to do? Change all of my primary keys to 'id' (will that solve the problem without causing some other problem I am not aware of). Or should I add some lines of code in doctrine_pi.php?

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• Monotouch threads, GC, WCF

  - by cvista

  Hi This is a question about best practices i guess but it applies directly to my current MT project. I'm using WCF services to communicate with the server. To do this i do the following: services.MethodToCall(params); and the asynch: services.OnMethodToCallCompleted += delegate{ //do stuff and ting }; This can lead to issues if you're not careful in that variables defined within the scope of the asynch callback can sometimes be cleaned up by the gc and this can cause crashes. So - I am making it a practice to declare these outside of the scope of the callback unless I am 100% sure they are not needed. Now - when doing stuff and ting implies changing the ui - i wrap it all in an InvokeOnMainThread call. I guess wrapping everything in this would slow the main thread down and rubbish the point of having multi threads. Even though I'm being careful about all this i am still getting crashes and I have no idea why! I am certain it has something to do with threads, scope and all that. Now - the only thing I can think of outside of updating the UI that may need to happen inside of InvokeOnMainThread is that I have a singleton 'Database' class. This is based on the version 5 code from this thread http://www.yoda.arachsys.com/csharp/singleton.html So now if the service method returns data that needs to be added/updated to the Database class -I also wrap this inside an InvokeOnMainThread call. Still getting random crashes. So... My question is this: I am new to thick client dev - I'm coming from a web dev perspective where we don't need to worry about threads so much :) Aside from what I have mentioned -are there any other things I should be aware of? Is the above stuff correct? Or am i miss-understanding something? Cheers w://

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• SQL Server Express performance issue

  - by Developer IT

  Hi folks ! I know my questions will sound silly and probably nobody will have perfect answer but since I am in a complete dead-end with the situation it will make me feel better to post it here. So... I have a SQL Server Express database that's 500 Mb. It contains 5 tables and maybe 30 stored procedure. This database is use to store articles and is use for the Developer It web site. Normally the web pages load quickly, let's say 2 ou 3 sec. BUT, sqlserver process uses 100% of the processor for those 2 or 3 sec. I try to find which stored procedure was the problem and I could not find one. It seems like every read into the table dans contains the articles (there are about 155,000 of them and 20 or so gets added every 15 minutes). I added few index but without luck... It is because the table is full text indexed ? Should I have order with the primary key instead of date ? I never had any problems with ordering by dates.... Should I use dynamic SQL ? Should I add the primary key into the url of the articles ? Should I use mutiple indexes for seperate columns or one big index ? I you want more details or code bits, just ask for it. Basicly, every little hint is much apreciated. Thanks.

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• .NET - Is there a way to programmatically fill all tables in a strongly-typed dataset?

  - by Mike Loux

  Hello, all! I have a SQL Server database for which I have created a strongly-typed DataSet (using the DataSet Designer in Visual Studio 2008), so all the adapters and select commands and whatnot were created for me by the wizard. It's a small database with largely static data, so I would like to pull the contents of this DB in its entirety into my application at startup, and then grab individual pieces of data as needed using LINQ. Rather than hard-code each adapter Fill call, I would like to see if there is a way to automate this (possibly via Reflection). So, instead of: Dim _ds As New dsTest dsTestTableAdapters.Table1TableAdapter.Fill(_ds.Table1) dsTestTableAdapters.Table2TableAdapter.Fill(_ds.Table2) <etc etc etc> I would prefer to do something like: Dim _ds As New dsTest For Each tableName As String In _ds.Tables Dim adapter as Object = <routine to grab adapter associated with the table> adapter.Fill(tableName) Next Is that even remotely doable? I have done a fair amount of searching, and I wouldn't think this would be an uncommon request, but I must be either asking the wrong question, or I'm just weird to want to do this. I will admit that I usually prefer to use unbound controls and not go with strongly-typed datasets (I prefer to write SQL directly), but my company wants to go this route, so I'm researching it. I think the idea is that as tables are added, we can just refresh the DataSet using the Designer in Visual Studio and not have to make too many underlying DB code changes. Any help at all would be most appreciated. Thanks in advance!

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• How to define a "complicated" ComputedColumn in SQL Server?

  - by Slauma

  SQL Server Beginner question: I'm trying to introduce a computed column in SQL Server (2008). In the table designer of SQL Server Management Studio I can do this, but the designer only offers me one single edit cell to define the expression for this column. Since my computed column will be rather complicated (depending on several database fields and with some case differentiations) I'd like to have a more comfortable and maintainable way to enter the column definition (including line breaks for formatting and so on). I've seen there is an option to define functions in SQL Server (scalar value or table value functions). Is it perhaps better to define such a function and use this function as the column specification? And what kind of function (scalar value, table value)? To make a simplified example: I have two database columns: DateTime1 (smalldatetime, NULL) DateTime2 (smalldatetime, NULL) Now I want to define a computed column "Status" which can have four possible values. In Dummy language: if (DateTime1 IS NULL and DateTime2 IS NULL) set Status = 0 else if (DateTime1 IS NULL and DateTime2 IS NOT NULL) set Status = 1 else if (DateTime1 IS NOT NULL and DateTime2 IS NULL) set Status = 2 else set Status = 3 Ideally I would like to have a function GetStatus() which can access the different column values of the table row which I want to compute the value of "Status" for, and then only define the computed column specification as GetStatus() without parameters. Is that possible at all? Or what is the best way to work with "complicated" computed column definitions? Thank you for tips in advance!

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• jQuery dynamically created table rows not responding to events

  - by mithunmo

  I have a table with one row in my HTML file. Now in jQuery I append lot of rows based on the data in the database. But the anchor tag which is created dynamically doesn't respond to events. How do I make this anchor tag respond to events? jQuery part //Appending rows from the Database $('<tr> <td> </td> <td id="log'+i+'"><a href="viewlog.php" target="_blank">log</a></td></tr> ').appendTo('#container'); Event part in jQuery Now when I write a line of code like this it does not respond. $('#container a ').click(function() { alert("Coming here "); }); //HTML <html> <table id="container"> <tr> <td> Name </td> <td> Link </td> </tr> </table> </html>

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• Problems sorting by date

  - by Nathan

  I'm attempting to only display data added to my database 24 hours ago or less. However, for some reason, the code I've written isn't working, and both entries in my database, one from 1 hour ago, one from 2 days ago, show up. Is there something wrong with my equation? Thanks! public void UpdateValues() { double TotalCost = 0; double TotalEarned = 0; double TotalProfit = 0; double TotalHST = 0; for (int i = 0; i <= Program.TransactionList.Count - 1; i++) { DateTime Today = DateTime.Now; DateTime Jan2013 = DateTime.Parse("01-01-2013"); //Hours since Jan12013 int TodayHoursSince2013 = Convert.ToInt32(Math.Round(Today.Subtract(Jan2013).TotalHours)); //7 int ItemHoursSince2013 = Program.TransactionList[i].HoursSince2013; //Equals 7176, and 7130 if (ItemHoursSince2013 - TodayHoursSince2013 <= 24) { TotalCost += Program.TransactionList[i].TotalCost; TotalEarned += Program.TransactionList[i].TotalEarned; TotalProfit += Program.TransactionList[i].TotalEarned - Program.TransactionList[i].TotalCost; TotalHST += Program.TransactionList[i].TotalHST; } } label6.Text = "$" + String.Format("{0:0.00}", TotalCost); label7.Text = "$" + String.Format("{0:0.00}", TotalEarned); label8.Text = "$" + String.Format("{0:0.00}", TotalProfit); label10.Text = "$" + String.Format("{0:0.00}", TotalHST); }

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• Rails running multiple delayed_job - lock tables

  - by pepernik

  Hey. I use delayed_job for background processing. I have 8 CPU server, MySQL and I start 7 delayed_job processes RAILS_ENV=production script/delayed_job -n 7 start Q1: I'm wondering is it possible that 2 or more delayed_job processes start processing the same process (the same record-row in the database delayed_jobs). I checked the code of the delayed_job plugin but can not find the lock directive in a way it should be. I think each process should lock the database table before executing an UPDATE on lock_by column. They lock the record simply by updating the locked_by field (UPDATE delayed_jobs SET locked_by...). Is that really enough? No locking needed? Why? I know that UPDATE has higher priority than SELECT but I think this does not have the effect in this case. My understanding of the multy-threaded situation is: Process1: Get waiting job X. [OK] Process2: Get waiting jobs X. [OK] Process1: Update locked_by field. [OK] Process2: Update locked_by field. [OK] Process1: Get waiting job X. [Already processed] Process2: Get waiting jobs X. [Already processed] I think in some cases more jobs can get the same information and can start processing the same process. Q2: Is 7 delayed_jobs a good number for 8CPU server? Why yes/not. Thx 10x!

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• Access 2007 DAO VBA Error 3381 causes objects in calling methods to "break".

  - by MT

  ---AFTER FURTHER INVESTIGATION--- "tblABC" in the below example must be a linked table (to another Access database). If "tblABC" is in the same database as the code then the problem does not occur. Hi, We have recently upgraded to Office 2007. We have a method in which we have an open recordset (DAO). We then call another sub (UpdatingSub below) that executes SQL. This method has its own error handler. If error 3381 is encountered then the recordset in the calling method becomes "unset" and we get error 3420 'Object invalid or no longer set'. Other errors in UpdatingSub do not cause the same problem. This code works fine in Access 2003. Private Sub Whatonearth() Dim rs As dao.Recordset set rs = CurrentDb.OpenRecordset("tblLinkedABC") Debug.Print rs.RecordCount UpdatingSub "ALTER TABLE tblTest DROP Column ColumnNotThere" 'Error 3240 occurs on the below line even though err 3381 is trapped in the calling procedure 'This appears to be because error 3381 is encountered when calling UpdatingSub above Debug.Print rs.RecordCount End Sub Private Sub WhatonearthThatWorks() Dim rs As dao.Recordset set rs = CurrentDb.OpenRecordset("tblLinkedABC") Debug.Print rs.RecordCount 'Change the update to generate a different error UpdatingSub "NONSENSE SQL STATEMENT" 'Error is trapped in UpdatingSub. Next line works fine. Debug.Print rs.RecordCount End Sub Private Sub UpdatingSub(strSQL As String) On Error GoTo ErrHandler: CurrentDb.Execute strSQL ErrHandler: 'LogError' End Sub Any thoughts? We are running Office Access 2007 (12.0.6211.1000) SP1 MSO (12.0.6425.1000). Perhaps see if SP2 can be distributed? Sorry about formatting - not sure how to fix that.

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• Where should I put contextual data related to an Object that is not really a property of the object?

  - by RenderIn

  I have a Car class. It has three properties: id, color and model. In a particular query I want to return all the cars and their properties, and I also want to return a true/false field called "searcherKnowsOwner" which is a field I calculate in my database query based on whether or not the individual conducting the search knows the owner. I have a database function that takes the ID of the searcher and the ID of the car and returns a boolean. My car class looks like this (pseudocode): class Car{ int id; Color color; Model model; } I have a screen where I want to display all the cars, but I also want to display a flag next to each car if the person viewing the page knows the owner of that car. Should I add a field to the Car class, a boolean searcherKnowsOwner? It's not a property of the car, but is actually a property of the user conducting the search. But this seems like the most efficient place to put this information.

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• The instruction at "0x7c910a19" referenced memory at "oxffffffff". The memory could not be "read"

  - by ClareBear

  Hello guys/girls The instruction at "0x7c910a19" referenced memory at "oxffffffff". The memory could not be "read" I have a small issue, I receive the error above before the .vbs terminates. I don't know why this error is thrown. Below is the process of the .vbs file: Call ImportTransactions() Call UpdateTransactions() Function ImportTransactions() Dim objConnection, objCommand, objRecordset, strOracle Dim strSQL, objRecordsetInsert Set objConnection = CreateObject("ADODB.Connection") objConnection.Open "DSN=*****;UID=*****;PWD==*****;" Set objCommand = CreateObject("ADODB.Command") Set objRecordset = CreateObject("ADODB.Recordset") strOracle = "SELECT query here from Oracle database" objCommand.CommandText = strOracle objCommand.CommandType = 1 objCommand.CommandTimeout = 0 Set objCommand.ActiveConnection = objConnection objRecordset.cursorType = 0 objRecordset.cursorlocation = 3 objRecordset.Open objCommand, , 1, 3 If objRecordset.EOF = False Then Do Until objRecordset.EOF = True strSQL = "INSERT query here into SQL database" strSQL = Query(strSQL) Call RunSQL(strSQL, objRecordsetInsert, False, conTimeOut, conServer, conDatabase, conUsername, conPassword) objRecordset.MoveNext Loop End If objRecordset.Close() Set objRecordset = Nothing Set objRecordsetInsert = Nothing End Function Function UpdateTransactions() Dim strSQLUpdateVAT, strSQLUpdateCodes Dim objRecordsetVAT, objRecordsetUpdateCodes strSQLUpdateVAT = "UPDATE query here SET [value:costing output] = ([value:costing output] * -1)" Call RunSQL(strSQLUpdateVAT, objRecordsetVAT, False, conTimeOut, conServer, conDatabase, conUsername, conPassword) strSQLUpdateCodes = "UPDATE query here SET [value:costing output] = ([value:costing output] * -1) different WHERE clause" Call RunSQL(strSQLUpdateCodes, objRecordsetUpdateCodes, False, conTimeOut, conServer, conDatabase, conUsername, conPassword) Set objRecordsetVAT = Nothing Set objRecordsetUpdateCodes = Nothing End Function UDPATE: If I exit the function after I open the connection (see below) it still causes the same error. Function ImportTransactions() Dim objConnection, objCommand, objRecordset, strOracle Dim strSQL, objRecordsetInsert Set objConnection = CreateObject("ADODB.Connection") objConnection.Open "DSN=*****;UID=*****;PWD==*****;" Set objCommand = CreateObject("ADODB.Command") Set objRecordset = CreateObject("ADODB.Recordset") Exit Function End Function It does both the import and update and seems to throw this error after. Thanks in advance for any help, Clare

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• Deeply nested subqueries for traversing trees in MySQL

  - by nickf

  I have a table in my database where I store a tree structure using the hybrid Nested Set (MPTT) model (the one which has lft and rght values) and the Adjacency List model (storing parent_id on each node). my_table (id, parent_id, lft, rght, alias) This question doesn't relate to any of the MPTT aspects of the tree but I thought I'd leave it in in case anyone had a good idea about how to leverage that. I want to convert a path of aliases to a specific node. For example: "users.admins.nickf" would find the node with alias "nickf" which is a child of one with alias "admins" which is a child of "users" which is at the root. There is a unique index on (parent_id, alias). I started out by writing the function so it would split the path to its parts, then query the database one by one: SELECT `id` FROM `my_table` WHERE `parent_id` IS NULL AND `alias` = 'users';-- 1 SELECT `id` FROM `my_table` WHERE `parent_id` = 1 AND `alias` = 'admins'; -- 8 SELECT `id` FROM `my_table` WHERE `parent_id` = 8 AND `alias` = 'nickf'; -- 37 But then I realised I could do it with a single query, using a variable amount of nesting: SELECT `id` FROM `my_table` WHERE `parent_id` = ( SELECT `id` FROM `my_table` WHERE `parent_id` = ( SELECT `id` FROM `my_table` WHERE `parent_id` IS NULL AND `alias` = 'users' ) AND `alias` = 'admins' ) AND `alias` = 'nickf'; Since the number of sub-queries is dependent on the number of steps in the path, am I going to run into issues with having too many subqueries? (If there even is such a thing) Are there any better/smarter ways to perform this query?

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• Ditching Django's models for Ajax/Web Services

  - by Igor Ganapolsky

  Recently I came across a problem at work that made me rethink Django's models. The app I am developing resides on a Linux server. Its a simple model/view/controller app that involves user interaction and updating data in the database. The problem is that this data resides in a MS SQL database on a Windows machine. So in order to use Django's models, I would have to leverage an ODBC driver on linux, and the use a python add-on like pyodbc. Well, let me tell you, setting up a reliable and functional ODBC connection on linux is no easy feat! So much so, that I spent several hours maneuvering this on my CentOS with no luck, and was left with frustration and lots of dumb system errors. In the meantime I have a deadline to meet, and suddenly the very agile and rapid Django application is a roadblock rather than a pleasure to work with. Someone on my team suggested writing this app in .NET. But there are a few problems with that: it won't be deployable on a linux machine, and I won't be able to work on it since I don't know ASP.net. Then a much better suggestion was made: keep the app in django, but instead of using models, do straight up ajax/web services calls in the template. And then it dawned on me - what a great idea. Django's models seem like a nuissance and hindrance in this case, and I can just have someone else write .Net services on their side, that I can call from my template. As a result my app will be leaner and more compact. So, I was wondering if you guys ever came across a similar dillema and what you decided to do about it.

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• MySql: Query multiple identical dynamic tables.

  - by JYelton

  I have a database with 500+ tables, each with identical structure, that contain historical data from sensors. I am trying to come up with a query that will locate, for example, all instances where sensor n exceeds x. The problem is that the tables are dynamic, the query must be able to dynamically obtain the list of tables. I can query information_schema.tables to get a list of the tables, like so: SELECT table_name FROM information_schema.tables WHERE table_schema = 'database_name'; I can use this to create a loop in the program and then query the database repeatedly, however it seems like there should be a way to have MySql do the multiple table search. I have not been able to make a stored procedure that works, but the examples I can find are generally for searching for a string in any column. I want to specifically find data in a specific column that exists in all tables. I admit I do not understand how to properly use stored procedures nor if they are the appropriate solution to this problem. An example query inside the loop would be: SELECT device_name, sensor_value FROM device_table WHERE sensor_value > 10; Trying the following does not work: SELECT device_name, sensor_value FROM ( SELECT table_name FROM information_schema.tables WHERE table_schema = 'database_name' ) WHERE sensor_value > 10; It results in an error: "Every derived table must have its own alias." The goal is to have a list of all devices that have had a given sensor value occur anywhere in their log (table). Ultimately, should I just loop in my program once I've obtained a list of tables, or is there a query structure that would be more efficient?

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• DB2 Driver Connection Hanging in Glassfish Connection Pool

  - by Ant

  We have an intermittent issue around the DB2 used from a Glassfish connection pool. What happens is this: Under situations where the database (DB2 on ZOS) is under stress, our application (which is a multi-threaded application using connections to DB2 via a Glassfish connection pool) stops doing anything. The following are observed: 1) Looking at the server using JConsole, we can see a thread waiting indefinitely in the DB2 driver's getConnection() method. We can also see that it has gained a lock on a Vector within the driver. Several other threads are also calling the getConnection() method in the driver, and are hanging waiting for the lock on the Vector to be released. 2) Looking at the database itself, we can see that there are connections from the Glassfish server open and waiting to be used. It seems that there is some sort of mismatch between the connection pool on Glassfish and the connections actually open to DB2. Has anyone come across this issue before? Or something similar? If you need any more information that I haven't provided, then please let me know!

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• IIS Restrict Access to Directory for table of users

  - by Dave

  I am trying to restrict access to files in a directory and it's sub directories based user rights. My user rights are stored in an MS SQL database in a custom format, however it is easy to query the list of users with rights to this directory. I need to know how to apply this to a web config on the server to authenticate against a query of a database table to determine if the username is authenticated and allowed to view the file. Of course if they are not they should be blocked / given a 404. I am using IIS and ASP.Net MVC3 with a form based security as opposed to the built in roles and responsibilities that was custom made for us and that works great. There are over 10k users tied to this non-Active Directory authentication so I am not planning to change my authentication type so please don't go there. It is not my decision on the choice of platform, or I would have gone with a LAMP server and been done with this. Edit 11-13-2012 @ 8:57a: In the web config can you put the result of an SQL query?

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• Good practice to create extension methods that apply to System.Object?

  - by Christian

  Hello, I'm wondering whether I should create extension methods that apply on the object level or whether they should be located at a lower point in the class hierarchy. What I mean is something along the lines of: public static string SafeToString(this Object o) { if (o == null || o is System.DBNull) return ""; else { if (o is string) return (string)o; else return ""; } } public static int SafeToInt(this Object o) { if (o == null || o is System.DBNull) return 0; else { if (o.IsNumeric()) return Convert.ToInt32(o); else return 0; } } //same for double.. etc I wrote those methods since I have to deal a lot with database data (From the OleDbDataReader) that can be null (shouldn't, though) since the underlying database is unfortunately very liberal with columns that may be null. And to make my life a little easier, I came up with those extension methods. What I'd like to know is whether this is good style, acceptable style or bad style. I kinda have my worries about it since it kinda "pollutes" the Object-class. Thank you in advance & Best Regards :) Christian P.S. I didn't tag it as "subjective" intentionally.

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