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  • Aggregate Functions in Index with IBMDB2

    - by Erkan
    Is there any way to pre aggregate results of aggregate functionts (f.i. count()) and store it in an index? The background is: i want to speed up count() queries. So that: Select count(users) from TE123 where region = 'A'; would be supported by an index like Region Count(Users) A 548 E 458 I know that MQTs would also help for this problem. However, in this case it is not possible to use MQT, as we use kind of an ORM and we don't want to define Entities on MQTs. I just slightly remember - one DBA told me - that there is such a function planned for DB2 V10.

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  • Strange use of the index in Mysql

    - by user309067
    explain SELECT feed_objects.* FROM feed_objects WHERE (feed_objects.feed_id IN (165,160,159,158,157,153,152,151,150,149,148,147,129,128,127,126,125,124,122,121,120,119,118,117,116,115,114,113,111,110)) ; +----+-------------+--------------+------+---------------+------+---------+------+------+-------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+--------------+------+---------------+------+---------+------+------+-------------+ | 1 | SIMPLE | feed_objects | ALL | by_feed_id | NULL | NULL | NULL | 188 | Using where | +----+-------------+--------------+------+---------------+------+---------+------+------+-------------+ Not used index 'by_feed_id' But when I point less than the values in the "WHERE" - everything is working right explain SELECT feed_objects.* FROM feed_objects WHERE (feed_objects.feed_id IN (165,160,159,158,157,153,152,151,150,149,148,147,129,128,127,125,124)) ; +----+-------------+--------------+-------+---------------+------------+---------+------+------+-------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+--------------+-------+---------------+------------+---------+------+------+-------------+ | 1 | SIMPLE | feed_objects | range | by_feed_id | by_feed_id | 9 | NULL | 18 | Using where | +----+-------------+--------------+-------+---------------+------------+---------+------+------+-------------+ Used index 'by_feed_id' What is the problem?

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  • Any way to optimize this MySQL query?

    - by manyxcxi
    My table looks like this: `MyDB`.`Details` ( `id` bigint(20) NOT NULL, `run_id` int(11) NOT NULL, `element_name` varchar(255) NOT NULL, `value` text, `line_order` int(11) default NULL, `column_order` int(11) default NULL ); I have the following SELECT statement in a stored procedure SELECT RULE ,TITLE ,SUM(IF(t.PASSED='Y',1,0)) AS PASS ,SUM(IF(t.PASSED='N',1,0)) AS FAIL FROM ( SELECT a.line_order ,MAX(CASE WHEN a.element_name = 'PASSED' THEN a.`value` END) AS PASSED ,MAX(CASE WHEN a.element_name = 'RULE' THEN a.`value` END) AS RULE ,MAX(CASE WHEN a.element_name = 'TITLE' THEN a.`value` END) AS TITLE FROM Details a WHERE run_id = runId GROUP BY line_order ) t GROUP BY RULE, TITLE; *runId is an input parameter to the stored procedure. This query takes about 14 seconds to run. The table has 214856 rows, and the particular run_id I am filtering on has 162204 records. It's not on a super high power machine, but I feel like I could be doing this more efficiently. My main goal is to summarize by Rule and Title and show Pass and Fail count columns.

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  • Why might one app connect to SQL backend OK and a second app fail if they share the same connectionstring?

    - by hawbsl
    Trying to figure out a SQL connection error 26 in our app. We've got two closely related apps Foo and FooAddIn. Foo is a Winforms app built in VS2010 and runs fine and connects fine to our SQLExpress back end. FooAddIn is an Outlook AddIn which references Foo.exe and connects to the same SQL Express instance. Or rather, it doesn't connect, instead reporting: A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: SQL Network Interfaces, error: 26 - Error Locating Server/Instance Specified) Now, both apps share the same connectionstring and we've verified they really do share the same connectionstring. At this stage we're just testing from within the same developer machine, so the apps are on the same machine, going via the same VS2010 IDE. So a lot of the advice online for this error doesn't apply because the fact that Foo connects through to SQL Express tells us the database is there and available and can be reached. What else is there to check? One thing is that Foo and FooAddIn are running different runtime versions of System.Data (v2.0.50727 and v4.0.30319). Could that be a factor?

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  • data filter using dataloadoptions

    - by Tassadaque
    Using dataloadoptions i have tried the following example Northwnd db = new Northwnd(@"northwnd.mdf"); // Preload Orders for Customer. // One directive per relationship to be preloaded. DataLoadOptions ds = new DataLoadOptions(); ds.LoadWith<Customer>(c => c.Orders); ds.AssociateWith<Customer> (c => c.Orders.Where(p => p.ShippedDate != DateTime.Today)); db.LoadOptions = ds; var custQuery = from cust in db.Customers where cust.City == "London" select cust; foreach (Customer custObj in custQuery) { Console.WriteLine("Customer ID: {0}", custObj.CustomerID); foreach (Order ord in custObj.Orders) { Console.WriteLine("\tOrder ID: {0}", ord.OrderID); foreach (OrderDetail detail in ord.OrderDetails) { Console.WriteLine("\t\tProduct ID: {0}", detail.ProductID); } } } Now i need to ask how can i display Category ID and Category Name of the productID (i am supposing that One product can be in at most one category) by extending the above example Regards

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  • Get DTS Step Description from TSQL?

    - by vikasde
    I am trying to get the DTS Step Name/Description of a given DTS Package in SQL2000. I am not able to see anything in the msdb database. I can see the initial DTS name, however I dont see anything to get the details. Anybody knows where this info is stored?

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  • How to write my own global lock / unlock functions for PostgreSQL

    - by rafalmag
    I have postgresql (in perlu) function getTravelTime(integer, timestamp), which tries to select data for specified ID and timestamp. If there are no data or if data is old, it downloads them from external server (downloading time ~300ms). Multiple process use this database and this function. There is an error when two process do not find data and download them and try to do an insert to travel_time table (id and timestamp pair have to be unique). I thought about locks. Locking whole table would block all processes and allow only one to proceed. I need to lock only on id and timestamp. pg_advisory_lock seems to lock only in "current session". But my processes uses their own sessions. I tried to write my own lock/unlock functions. Am I doing it right? I use active waiting, how can I omit this? Maybe there is a way to use pg_advisory_lock() as global lock? My code: CREATE TABLE travel_time_locks ( id_key integer NOT NULL, time_key timestamp without time zone NOT NULL, UNIQUE (id_key, time_key) ); ------------ -- Function: mylock(integer, timestamp) DROP FUNCTION IF EXISTS mylock(integer, timestamp) CASCADE; -- Usage: SELECT mylock(1, '2010-03-28T19:45'); -- function tries to do a global lock similar to pg_advisory_lock(key, key) CREATE OR REPLACE FUNCTION mylock(id_input integer, time_input timestamp) RETURNS void AS $BODY$ DECLARE rows int; BEGIN LOOP BEGIN -- active waiting here !!!! :( INSERT INTO travel_time_locks (id_key, time_key) VALUES (id_input, time_input); EXCEPTION WHEN unique_violation THEN CONTINUE; END; EXIT; END LOOP; END; $BODY$ LANGUAGE 'plpgsql' VOLATILE COST 1; ------------ -- Function: myunlock(integer, timestamp) DROP FUNCTION IF EXISTS myunlock(integer, timestamp) CASCADE; -- Usage: SELECT myunlock(1, '2010-03-28T19:45'); -- function tries to do a global unlock similar to pg_advisory_unlock(key, key) CREATE OR REPLACE FUNCTION myunlock(id_input integer, time_input timestamp) RETURNS integer AS $BODY$ DECLARE BEGIN DELETE FROM ONLY travel_time_locks WHERE id_key=id_input AND time_key=time_input; RETURN 1; END; $BODY$ LANGUAGE 'plpgsql' VOLATILE COST 1;

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  • update query with join on two tables

    - by dba_query
    I have customer and address tables. query: select * from addresses a, customers b where a.id = b.id returns 474 records For these records, I'd like to add the id of customer table into cid of address table. Example: If for the first record the id of customer is 9 and id of address is also 9 then i'd like to insert 9 into cid column of address table. I tried: update addresses a, customers b set a.cid = b.id where a.id = b.id but this does not seem to work.

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  • Advice on Linq to SQL mapping object design

    - by fearofawhackplanet
    I hope the title and following text are clear, I'm not very familiar with the correct terms so please correct me if I get anything wrong. I'm using Linq ORM for the first time and am wondering how to address the following. Say I have two DB tables: User ---- Id Name Phone ----- Id UserId Model The Linq code generator produces a bunch of entity classes. I then write my own classes and interfaces which wrap these Linq classes: class DatabaseUser : IUser { public DatabaseUser(User user) { _user = user; } public Guid Id { get { return _user.Id; } } ... etc } so far so good. Now it's easy enough to find a users phones from Phones.Where(p => p.User = user) but surely comsumers of the API shouldn't need to be writing their own Linq queries to get at data, so I should wrap this query in a function or property somewhere. So the question is, in this example, would you add a Phones property to IUser or not? In other words, should my interface specifically be modelling my database objects (in which case Phones doesn't belong in IUser), or are they actually simply providing a set of functions and properties which are conceptually associated with a User (in which case it does)? There seems drawbacks to both views, but I'm wondering if there is a standard approach to the problem. Or just any general words of wisdom you could share. My first thought was to use extension methods but in fact that doesn't work in this case.

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  • Looking for MSSQL Table Design Sanity Check for Profile Tables with Dynamic Columns.

    - by Code Sherpa
    I just want a general sanity check regarding database design. We are building a web system that has both Teachers and Students. Both have accounts in the system. Both have profiles in the system. My question is about the table design of those Profile tables. The Teacher profile is pretty static regarding the metadata associated with it. Each teacher has a set number of fields that exposes information about that individual (schools, degrees, etc). The students, however, are a different case. We are using a windows service to pull varying data about the students from an endless stream of excel spreadsheets. The data gets moved into our database and then the fields appear in association with the student's profile. Accordingly, each and every student may have very different fields in their profile. I originally started with the concept of three tables: Accounts ---------- AccountID TeacherProfiles ---------- TeacherProfileID AccountID SecondarySchool University YearsTeaching Etc... StudentProfiles ---------- StudentProfileID AccountID Header Value The StudentProfiles table would hold the name of the column headers from the excel spreadsheets and the associated values. I have since evolved the design a little to treat Profiles more generically per the attached ERD image. The Teacher and Student "Headers" are stored in a table called "ProfileAttributeTypes" and responses (either from the excel document or via input fields on the web form) are put in a ProfileAttributes table. This way both Student and Teacher profiles can be associated with a dynamic flow of profile fields. The "Permissions" table tells us whether we are dealing with a Student or a Teacher. Since this system is likely to grow quickly, I want to make sure the foundation is solid. Can you please provide feedback about this design and let me know if it seems sound or if you could see problems it might create and, if so, what might be a better approach? Thanks in advance.

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  • VB.NET: SQLite to MSSQL

    - by user1736785
    I have a vb.net project that uses a SQLite database. I do this by using dataset/table adapters. The client is happy and all works well. However I have just heard that they plan on providing this product to another customer that wishes to use their MSSQL database. So I am writing this post so I can mentally prepare for this before I begin. I am not a database pro and have really enjoyed the simplicity of setting up and managing an SQLite database. So any ideas on the easiest way to support MSSQL as well? I am happy to run them parallel to each other. Can I just make a separate service / middleware that syncs the SQLite database to the MSSQL on a timer and does not care about what the main app is up to? Any pointers are appreciated.

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  • Why doesn't SQL LIKE work in Microsoft Access?

    - by poo
    I want to my make a search-statement and query things like this select * from table where col like '%vkvk%' But with trial and error I've come to the conclusion that access doesn't work with LIKE or wildcard operators. Does anybody have some other solutions because I ain't so in to access actually, so I really don't know.

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  • Does anybody have any suggestions on which of these two approaches is better for large delete?

    - by RPS
    Approach #1: DECLARE @count int SET @count = 2000 DECLARE @rowcount int SET @rowcount = @count WHILE @rowcount = @count BEGIN DELETE TOP (@count) FROM ProductOrderInfo WHERE ProductId = @product_id AND bCopied = 1 AND FileNameCRC = @localNameCrc SELECT @rowcount = @@ROWCOUNT WAITFOR DELAY '000:00:00.400' Approach #2: DECLARE @count int SET @count = 2000 DECLARE @rowcount int SET @rowcount = @count WHILE @rowcount = @count BEGIN DELETE FROM ProductOrderInfo WHERE ProductId = @product_id AND FileNameCRC IN ( SELECT TOP(@count) FileNameCRC FROM ProductOrderInfo WITH (NOLOCK) WHERE bCopied = 1 AND FileNameCRC = @localNameCrc ) SELECT @rowcount = @@ROWCOUNT WAITFOR DELAY '000:00:00.400' END

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  • Indexing affects only the WHERE clause?

    - by andre matos
    If I have something like: CREATE INDEX idx_myTable_field_x ON myTable USING btree (field_x); SELECT COUNT(field_x), field_x FROM myTable GROUP BY field_x ORDER BY field_x; Imagine myTable with around 500,000 rows and most of field_x values being unique. Since I don't use any WHERE clause, will the created index have any effect at all in my query? Edit: I'm asking this question because I don't get any relevant difference between query-times before and after creating the index; They always take about 8 seconds (which, of course is too much time!). Is this behaviour expected?

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  • trouble connecting to MySql DB (PHP)

    - by user332817
    Hi I have the following PHP code to connect to my db. <?php ob_start(); $host="localhost"; // Host name $username="root"; // Mysql username $password=""; // Mysql password $db_name="test"; // Database name $tbl_name="members"; // Table name // Connect to server and select databse. mysql_connect("$host", "$username", "$password")or die("cannot connect"); ?> however I get the following error: Warning: mysql_connect() [function.mysql-connect]: [2002] A connection attempt failed because the connected party did not (trying to connect via tcp://localhost:3306) in C:\Program Files (x86)\EasyPHP-5.3.2i\www\checklogin.php on line 11 Warning: mysql_connect() [function.mysql-connect]: A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond. in C:\Program Files (x86)\EasyPHP-5.3.2i\www\checklogin.php on line 11 Fatal error: Maximum execution time of 30 seconds exceeded in C:\Program Files (x86)\EasyPHP-5.3.2i\www\checklogin.php on line 11 I am able to add a db/tables via phpmyadmin but I cant connect using php. here is a screenshot of my phpmyadmin page: http://img294.imageshack.us/img294/1589/sqls.jpg any help would be appreciated, thanks in advance.

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  • HQl equivalent of sql query

    - by kash
    String SQL_QUERY = "SELECT count(*) FROM (SELECT * FROM Url as U where U.pageType=" + 1 + " group by U.pageId having count(U.pageId) = 1)"; query = session.createQuery(SQL_QUERY); I am getting an error org.hibernate.hql.ast.QuerySyntaxException: unexpected token: ( near line 1, column 23 [ SELECT count() FROM (SELECT * FROM Url as U where U.pageType = 2 group by U.pageId having count(U.pageId) = 1)]

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  • Indexed key vs indexed separate columns, which one is faster ?

    - by Jerry
    In MYSQL, from a pure performance perspective, if I have a table with large amount of data with 10/1 read/write ratio. is it faster in read/write performance to have 4 search criteria in separate columns and all indexed or have them combined in to one single string acting as a key and store in one indexed column ? e.g. say this table with 5 columns, first name, last name, sex, country and file where the first four columns will ALWAYS be given as a part of search parameters in a search or have a table with two columns, key and file. where the value of key can be john-smith-male-australia ?? I don't quite get the pros and cons. the point I try to stress is the fact that all parameters will be given.in a search.

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  • What would be the best schema to store the 'address' for different entities?

    - by Cesar
    Suppose we're making a system where we have to store the addrees for buildings, persons, cars, etc. The address 'format' should be something like: State (From a State list) County (From a County List) Street (free text, like '5th Avenue') Number (free text, like 'Chrysler Building, Floor 10, Office No. 10') (Yes I don't live in U.S.A) What would be the best way to store that info: Should I have a Person_Address, Car_Address, ... Or the address info should be in columns on each entity, Could we have just one address table and try to link each row to a different entity? Or are there another 'better' way to handle this type of scenario? How would yo do it?

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  • DB Interface Design Optimization: Is it better to optimise for Fewer requests of smaller data size?

    - by Overflow
    The prevailing wisdom in webservices/web requests in general is to design your api such that you use as few requests as possible, and that each request returns therefore as much data as is needed In database design, the accepted wisdom is to design your queries to minimise size over the network, as opposed to minimizing the number of queries. They are both remote calls, so what gives?

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  • Syntax Error in showing Error Description

    - by Sreejesh Kumar
    What is the correct Syntax to be applied for "@[System::ErrorDescription]" inside the query like "INSERT" ? I am unable to retrieve the correct Error Description inside the table, as the result in the table is showing as "@[System::ErrorDescription]". I am not getting the result !

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  • What does P mean in Sort(Expression<Func<T, P>> expr, ListSortDirection direction)?

    - by Grasshopper
    I am attempting to use the answer in post: How do you sort an EntitySet<T> to expose an interface so that I can sort an EntitySet with a Binding list. I have created the class below and I get the following compiler error: "The type or namespace 'P' could not be found (are you missing a using directive or assembly reference?). Can someone tell me what the P means and which namespace I need to include to get the method below to compile? I am very new to delegates and lamba expressions. Also, can someone confirm that if I create a BindingList from my EntitySet that any modifications I make to the BindingList will be made to the EntitySet? Basically, I have an EntitySet that I need to sort and make changes to. Then, I will need to persist these changes using the original Entity that the BindingList came from. public class EntitySetBindingWrapper<T> : BindingList<T> { public EntitySetBindingWrapper(BindingList<T> root) : base(root) { } public void Sort(Expression<Func<T, P>> expr, ListSortDirection direction) { if (expr == null) base.RemoveSortCore(); MemberExpression propExpr = expr as MemberExpression; if (propExpr == null) throw new ArgumentException("You must provide a property", "expr"); PropertyDescriptorCollection descriptorCol = TypeDescriptor.GetProperties(typeof(T)); IEnumerable<PropertyDescriptor> descriptors = descriptorCol.Cast<PropertyDescriptor>(); PropertyDescriptor descriptor = descriptors.First(pd => pd.Name == propExpr.Member.Name); base.ApplySortCore(descriptor, direction); } }

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  • Update database in asp.net not working

    - by Badescu Alexandru
    Hello ! i have in asp.net a few textboxes and i wish to update my database with the values that they encapsulate . The problem is that it doesn't work and although it doesn't work, the syntax seems correct and there are no errors present . Here is my linkbutton : <asp:linkbutton id="clickOnSave" runat="server" onclick="Save_Click" Text="Save Profile" /> and my update function protected void Save_Click(object sender, EventArgs e) { SqlConnection con = new System.Data.SqlClient.SqlConnection(); con.ConnectionString = "DataSource=.\\SQLEXPRESS;AttachDbFilename=C:\\Users\\alex\\Documents\\seeubook_db.mdf;Integrated Security=True;Connect Timeout=30;User Instance=True"; con.Open(); String commandString = "UPDATE users SET last_name='" + Text4.Text.Trim() + "' , first_name='" + Textbox1.Text.Trim() + "' , about_me='" + Textbox5.Text.Trim() + "' , where_i_live='" + Textbox2.Text.Trim() + "' , where_i_was_born='" + Textbox3.Text.Trim() + "' , work_place='" + Textbox4.Text.Trim() + "' WHERE email='" + Session["user"] + "'"; SqlCommand sqlCmd = new SqlCommand(commandString, con); sqlCmd.ExecuteNonQuery(); con.Close(); }

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