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• Getting average from 3 columns in MS SQL

  - by barbarian

  I have table with 3 columns(smallint) in MS SQL 2005. Table Ratings ratin1 smallint, ratin2 smallint ratin3 smallint These columns can have values from 0 to 5 How to select average value of these fields, but only compare fields where value is greater then 0. So if column values are 1,3,5 - average had to be 3 if values are 0,3,5 - average had to be 4

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• Need help with a SQL Query

  - by Jack

  I have created a table with the following structure- $sql = "CREATE TABLE followers ( uid int UNSIGNED NOT NULL UNIQUE, PRIMARY KEY(uid), follower_count int UNSIGNED , is_my_friend bool, status_count int UNSIGNED, location varchar(50) )"; I need to find the uid of the person with max(status_count+follower_count) and whose is_my_friend = 1 I wrote the following query but I ain't getting the correct uid. SELECT p.uid FROM (select uid,is_my_friend,max(follower_count+status_count) from followers) p WHERE p.is_my_friend = 1;

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• Is there anyway that we can get a label value to a Sql

  - by Pradeep

  SELECT COUNT(*) AS Expr1 FROM Book INNER JOIN Temp_Order ON Book.Book_ID = Temp_Order.Book_ID WHERE (Temp_Order.User_ID = 25) AND (CONVERT (nvarchar, Temp_Order.OrderDate, 111) = CONVERT (nvarchar, GETDATE(), 111)) In here i want to change my User_ID to get from a label.Text this Sql Statement is in a DataView. so in the Wizard it not accepting a text box values or anything. can someone please help me to solve this

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• Problem using IIS 7 and SQL SERVER 2008

  - by Daniel

  I have problem using IIS 7 and SQL Server 2008. When I trying to show my website using IIS as webserver I get the message "[SqlException (0x80131904): Login failed for user..." When I using the webserver included in Visual Studio 2010 to show same website there is no problem to access the database. Why is it working with VS2010 webserver but not with IIS?

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• How to filter a duration in SQL Profiler

  - by user341460

  Hi Friends, I need to run a profiler on SQL 2005 to capture the SPs with which took longer than 1/10th of a second. Can you please let me know how can I do that. I dont see the option. Also in the duration is that measured in second or minute. I would apprecaite your help. Thanks,

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• What is wrong with this sql statement?

  - by chandru_cp

  I am trying to fetch records based on two dates from sql server... Select * from table where CreatedDate between @StartDate and @EndDate and i pass 5/12/2010 and 5/12/2010 (ie) fetching records for today... I have 17 records dated 5/12/2010 but none seems to get selected.... EDIT: I use this but when i debug my value it shows 5/12/2010 12:00:00AM DateTime baseDate = DateTime.Today; var today = baseDate; GetBookingReportByDate(today,today);

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• SQL University: What and why of database testing

  - by Mladen Prajdic

  This is a post for a great idea called SQL University started by Jorge Segarra also famously known as SqlChicken on Twitter. It’s a collection of blog posts on different database related topics contributed by several smart people all over the world. So this week is mine and we’ll be talking about database testing and refactoring. In 3 posts we’ll cover: SQLU part 1 - What and why of database testing SQLU part 2 - What and why of database refactoring SQLU part 2 – Tools of the trade With that out of the way let us sharpen our pencils and get going. Why test a database The sad state of the industry today is that there is very little emphasis on testing in general. Test driven development is still a small niche of the programming world while refactoring is even smaller. The cause of this is the inability of developers to convince themselves and their managers that writing tests is beneficial. At the moment they are mostly viewed as waste of time. This is because the average person (let’s not fool ourselves, we’re all average) is unable to think about lower future costs in relation to little more current work. It’s orders of magnitude easier to know about the current costs in relation to current amount of work. That’s why programmers convince themselves testing is a waste of time. However we have to ask ourselves what tests are really about? Maybe finding bugs? No, not really. If we introduce bugs, we’re likely to write test around those bugs too. But yes we can find some bugs with tests. The main point of tests is to have reproducible repeatability in our systems. By having a code base largely covered by tests we can know with better certainty what a small code change can break in other parts of the system. By having repeatability we can make code changes with confidence, since we know we’ll see what breaks in other tests. And here comes the inability to estimate future costs. By spending just a few more hours writing those tests we’d know instantly what broke where. Imagine we fix a reported bug. We check-in the code, deploy it and the users are happy. Until we get a call 2 weeks later about a certain monthly process has stopped working. What we don’t know is that this process was developed by a long gone coworker and for some reason it relied on that same bug we’ve happily fixed. There’s no way we could’ve known that. We say OK and go in and fix the monthly process. But what we have no clue about is that there’s this ETL job that relied on data from that monthly process. Now that we’ve fixed the process it’s giving unexpected (yet correct since we fixed it) data to the ETL job. So we have to fix that too. But there’s this part of the app we coded that relies on data from that exact ETL job. And just like that we enter the “Loop of maintenance horror”. With the loop eventually comes blame. Here’s a nice tip for all developers and DBAs out there: If you make a mistake man up and admit to it. All of the above is valid for any kind of software development. Keeping this in mind the database is nothing other than just a part of the application. But a big part! One reason why testing a database is even more important than testing an application is that one database is usually accessed from multiple applications and processes. This makes it the central and vital part of the enterprise software infrastructure. Knowing all this can we really afford not to have tests? What to test in a database Now that we’ve decided we’ll dive into this testing thing we have to ask ourselves what needs to be tested? The short answer is: everything. The long answer is: read on! There are 2 main ways of doing tests: Black box and White box testing. Black box testing means we have no idea how the system internals are built and we only have access to it’s inputs and outputs. With it we test that the internal changes to the system haven’t caused the input/output behavior of the system to change. The most important thing to test here are the edge conditions. It’s where most programs break. Having good edge condition tests we can be more confident that the systems changes won’t break. White box testing has the full knowledge of the system internals. With it we test the internal system changes, different states of the application, etc… White and Black box tests should be complementary to each other as they are very much interconnected. Testing database routines includes testing stored procedures, views, user defined functions and anything you use to access the data with. Database routines are your input/output interface to the database system. They count as black box testing. We test then for 2 things: Data and schema. When testing schema we only care about the columns and the data types they’re returning. After all the schema is the contract to the out side systems. If it changes we usually have to change the applications accessing it. One helpful T-SQL command when doing schema tests is SET FMTONLY ON. It tells the SQL Server to return only empty results sets. This speeds up tests because it doesn’t return any data to the client. After we’ve validated the schema we have to test the returned data. There no other way to do this but to have expected data known before the tests executes and comparing that data to the database routine output. Testing Authentication and Authorization helps us validate who has access to the SQL Server box (Authentication) and who has access to certain database objects (Authorization). For desktop applications and windows authentication this works well. But the biggest problem here are web apps. They usually connect to the database as a single user. Please ensure that that user is not SA or an account with admin privileges. That is just bad. Load testing ensures us that our database can handle peak loads. One often overlooked tool for load testing is Microsoft’s OSTRESS tool. It’s part of RML utilities (x86, x64) for SQL Server and can help determine if our database server can handle loads like 100 simultaneous users each doing 10 requests per second. SQL Profiler can also help us here by looking at why certain queries are slow and what to do to fix them.   One particular problem to think about is how to begin testing existing databases. First thing we have to do is to get to know those databases. We can’t test something when we don’t know how it works. To do this we have to talk to the users of the applications accessing the database, run SQL Profiler to see what queries are being run, use existing documentation to decipher all the object relationships, etc… The way to approach this is to choose one part of the database (say a logical grouping of tables that go together) and filter our traces accordingly. Once we’ve done that we move on to the next grouping and so on until we’ve covered the whole database. Then we move on to the next one. Database Testing is a topic that we can spent many hours discussing but let this be a nice intro to the world of database testing. See you in the next post.

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• In LINQ-SQL, wrap the DataContext is an using statement - pros cons

  - by hIpPy

  Can someone pitch in their opinion about pros/cons between wrapping the DataContext in an using statement or not in LINQ-SQL in terms of factors as performance, memory usage, ease of coding, right thing to do etc. Update: In one particular application, I experienced that, without wrapping the DataContext in using block, the amount of memory usage kept on increasing as the live objects were not released for GC. As in, in below example, if I hold the reference to List of q object and access entities of q, I create an object graph that is not released for GC. DataContext with using using (DBDataContext db = new DBDataContext()) { var q = from x in db.Tables where x.Id == someId select x; return q.toList(); } DataContext without using and kept alive DBDataContext db = new DBDataContext() var q = from x in db.Tables where x.Id == someId select x; return q.toList(); Thanks.

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• SQL 2003 Distance Latitude Longitude

  - by J.Hendrix

  I have a table full of Dealers along with their latitude and longitude. I am trying to determine the top n closest dealers to any given lat and lon. I already have the function to calculate distance between locations, but I want to do as few calculations as possible (my table can contain many thousands of entries). Currently I have to calculate the distance for each entry then sort them. Is there any way to sort before I do the calculation to improve performance? This question is good, but I will not always know my range. Should I just pick an arbitrarily high range then refine my results? I am thankful for any help the community can offer. declare @Lat real declare @lon real Set @lat = 41.05 Set @lon = -73.53 SELECT top 10 MemberID, Address1, City, State, Zip, Phone, Lat, Lon, (SELECT fun_DistanceLatLon] (@Lat,@lon,Lat,Lon)) as mDistance --Calculate distance FROM Dealers Order by (SELECT fun_DistanceLatLon] (@Lat,@lon,Lat,Lon))

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• SQL Server Installation - What is the Installation Media Folder..??

  - by Devashri

  I am installing SQL server 2008. I have installed .Net framewok 3.5. Then I got folder SQL Server 2008.Then I performed following steps- In that I clicked configuration Tools. Then I clicked SQL Server Installation Center. I clicked "Installation" hyperlink on left side. Then I clicked "New SQL server stand-alone installation or add features to an existing installation" Then i got a window "Browse for SQL server Installation Media" which folder should i choose..?? OR is there any other method to install SQL Server..??

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• How to avoid the same calculations on column values over and over again in a select?

  - by Peter

  I sometimes write SELECTs on the form: SELECT a.col1+b.col2*c.col4 as calc_col1, a.col1+b.col2*c.col4 + xxx as calc_col1_PLUS_MORE FROM .... INNER JOIN ... ON a.col1+b.col2*c.col4 < d.some_threshold WHERE a.col1+b.col2*c.col4 > 0 When the calculations get rather involved and used up to 3-5 times within the same SELECT, I would really like to refactor that out in a function or similar in order to 1) hopefully improve performance / make use of cache 2) avoid forgetting to update one of the 4 calculations when I at a later stage realize I need to change the calculation. I usually have these selects within SPs. Any ideas?

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• Best way to handle SQL Server fulltext index updates

  - by tlianza

  Hi all, I have a fulltext index which doesn't need to be immediately up-to-date, I'd like to spare myself the I/O (when I do bulk updates, I see a ton of I/O related to the index) and do the index updates during low usage times (nightly, perhaps even weekly). It seems there are two ways to go about this: Turn off change tracking (SET CHANGE_TRACKING OFF) and add a timestamp field to the indexed table, so that you can run alter fulltext index on <table> start INCREMENTAL population, or Enable change tracking, but set it to MANUAL, so that you can run alter fulltext index on <table> start UPDATE population when you need it updated. Is there a preferred method? I couldn't tell from this overview if there was a performance benefit one way or the other. Tom

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• Can I connect to SQL Server using Windows Authentication from Java EE webapp?

  - by KG

  I am currently investigating how to make a connection to a SQL Server database from my Java EE web application using Windows Authentication instead of SQL Server authentication. I am running this app off of Tomcat 6.0, and am utilizing the Microsoft JDBC driver. My connection properties file looks as follows: dbDriver = com.microsoft.sqlserver.jdbc.SQLServerDriver dbUser = user dbPass = password dbServer = localhost:1433;databaseName=testDb dbUrl = jdbc:sqlserver://localhost:1433 I have zero problems with connecting to a SQL Server database in this fashion when using SQL Server authentication. Is there any way I can retrieve the credentials of the user's Windows Authentication and use that authentication for SQL Server? UPDATE: I know in ASP.net there is a way to set up Windows Authentication for access to the webapp, which is exactly what I am looking for, except I want to pass that token off to SQL Server for access to the database.

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• Returning several COUNT results from one ASP SQL statement

  - by user89691

  Say I have a table like this: Field1 Field2 Field3 Field4 fred tom fred harry tom tom dick harry harry and I want to determine what proportion of it has been completed for each field. I can execute: SELECT COUNT (Field1) WHERE (Field1 <> '') AS Field1Count SELECT COUNT (Field2) WHERE (Field2 <> '') AS Field2Count SELECT COUNT (Field3) WHERE (Field3 <> '') AS Field3Count SELECT COUNT (Field4) WHERE (Field4 <> '') AS Field4Count Is it possible to roll up these separate SQL statements into one that will return the 4 results in one hit? Is there any performance advantage to doing so (given that the number of columns and rows may be quite large in practice)?

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• MS Sql Full-text search vs. LIKE expression

  - by Marks

  Hi. I'm currently looking for a way to search a big database (500MB - 10GB or more on 10 tables) with a lot of different fields(nvarchars and bigints). Many of the fields, that should be searched are not in the same table. An example: A search for '5124 Peter' should return all items, that ... have an ID with 5124 in it, have 'Peter' in the title or description have item type id with 5124 in it created by a user named 'peter' or a user whose id has 5124 in it created by a user with '5124' or 'peter' in his street address. How should i do the search? I read that the full-text search of MS-Sql is a lot more performant than a query with the LIKE keyword and i think the syntax is more clear, but i think it cant search on bigint(id) values and i read it has performance problems with indexing and therefore slows down inserts to the DB. In my project there will be more inserting than reading, so this could be a matter. Thanks in advance, Marks

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• Which can handle a huge surge of queries: SQL Server 2008 Fulltext or Lucene

  - by Luke101

  I am creating a widget that will be installed on several websites and blogs. The widget will analyse the remote webpage title and content, then it will return relevent articles/links on my website. The amount of traffic we expect will be very huge roughly 500K queries a day and up from there. I need the queries to be returned very quickly, so I need the candidate to be high performance, similar to google adsense. The remote title can be from 5 to 50 words and the description we will use no more then 3000 words. Which of these two do you think can handle the load.

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• Entity Framework How to specify paramter type in generated SQL (SQLServer 2005) Nvarchar vs Varchar

  - by Gratzy

  In entity framework I have an Entity 'Client' that was generated from a database. There is a property called 'Account' it is defined in the storage model as: <Property Name="Account" Type="char" Nullable="false" MaxLength="6" /> And in the Conceptual Model as: <Property Name="Account" Type="String" Nullable="false" /> When select statements are generated using a variable for Account i.e. where m.Account == myAccount... Entity Framework generates a paramaterized query with a paramater of type NVarchar(6). The problem is that the column in the table is data type of char(6). When this is executed there is a large performance hit because of the data type difference. Account is an index on the table and instead of using the index I believe an Index scan is done. Anyone know how to force EF to not use Unicode for the paramater and use Varchar(6) instead?

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• foreign key constraints on primary key columns - issues ?

  - by zzzeek

  What are the pros/cons from a performance/indexing/data management perspective of creating a one-to-one relationship between tables using the primary key on the child as foreign key, versus a pure surrogate primary key on the child? The first approach seems to reduce redundancy and nicely constrains the one-to-one implicitly, while the second approach seems to be favored by DBAs, even though it creates a second index: create table parent ( id integer primary key, data varchar(50) ) create table child ( id integer primary key references parent(id), data varchar(50) ) pure surrogate key: create table parent ( id integer primary key, data varchar(50) ) create table child ( id integer primary key, parent_id integer unique references parent(id), data varchar(50) ) the platforms of interest here are Postgresql, Microsoft SQL Server.

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• Oracle SQL Update query takes days to update

  - by B Senthil Kumar

  I am trying to update a record in the target table based on the record coming in from source. For instance, if the incoming record is present in the target table I would update them in the target else I would simply insert. I have over one million records in my source while my target has 46 million records. The target table is partitioned based on calendar key. I implement this whole logic using Informatica. I find that the Informatica code is perfectly fine looking at the Informatica session log but its in the update it takes long time (more than 5 days to update one million records). Any suggestions as to what can be done on the scenario to improve the performance?

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• Implications of Fulltext Search over many columns

  - by Alex

  Hello, I have a really wide table which includes separate columns for billing address, shipping address, primary address, names, aliases etc. (I can't normalize this table further, and that's not the question here anyways). I'm implementing SQL Server fulltext search, and I'm wondering whether I should limit the search ability to just the primary fields (primary address and names for example), or if I can extend the search ability across all columns without occurring too much of a performance or memory penalty. I've done some basic testing with 10,000 sample rows and it's quite fast but I don't have much experience with fulltext indexing, especially its dictionary internals, so I don't know if the index is going to grow over time, or if there is anything else to consider. Thoughts?

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• IF/ELSE makes stored procedure not return a result set

  - by Brendan Long

  I have a stored procedure that needs to return something from one of two databases: IF @x = 1 SELECT @y FROM Table_A ELSE IF @x = 2 SELECT @y FROM Table_B Either SELECT alone will return what I want, but adding the IF/ELSE makes it stop returning anything. I tried: IF @x = 1 RETURN SELECT @y FROM Table_A ELSE IF @x = 2 RETURN SELECT @y FROM Table_B But that causes a syntax error. The two options I see are both horrible: Do a UNION and make sure that only one side has any results: SELECT @y FROM Table_A WHERE @x = 1 UNION SELECT @y FROM Table_B WHERE @x = 2 Create a temporary table to store one row in, and create and delete it every time I run this procedure (lots). Neither solution is elegant, and I assume they would both be horrible for performance (unless MS SQL is smart enough not to search the tables when the WHERE class is always false). Is there anything else I can do? Is option 1 not as bad as I think?

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• Linq to SQL - design question.

  - by UshaP

  HI, Currently i have one big datacontex with 35 tables (i dragged all my DB tables to the designer). I must admit it is very comfortable cause i have ORM to my full DB and query with linq is easy and simple. My questions are: 1. Would you consider it bad design to have one datacontext with 35 tables or should i split it to logic units? 2. Is there any performance penalties for using such a big datacontext? Thanks, Pini.

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• Linq to SQL and Realtime Data

  - by Jeremy

  I have an application that needs to constantly (every 50ms), call to an MVC action, and pickup/drop off data. I am using Linq to SQL and MVC because of how simple they are to implement, and I know that they aren't perfect when it comes to performance, but it works relatively well, but the best speed I can get with my current approach is 200ms (without requests overlapping). Each call to the site will create a new instance of the datacontext, query/insert it and return that data. Is there a way to have the datacontext static, but submitchanges say every 5 seconds, so that i am pretty much hitting an in-memory version of the data?

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• Database design: one huge table or separate tables?

  - by littlegreen

  Currently I am designing a database for use in our company. We are using SQL Server 2008. The database will hold data gathered from several customers. The goal of the database is to acquire aggregate benchmark numbers over several customers. Recently, I have become worried with the fact that one table in particular will be getting very big. Each customer has approximately 20.000.000 rows of data, and there will soon be 30 customers in the database (if not more). A lot of queries will be done on this table. I am already noticing performance issues and users being temporarily locked out. My question, will we be able to handle this table in the future, or is it better to split this table up into smaller tables for each customer?

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• Multiple column foreign key contraints

  - by eugene4968

  I want to setup table constraints for the following scenario and I’m not sure how to do it or if it’s even possible in SQL Server 2005. I have three tables A,B,C. C is a child of B. B will have a optional foreign key(may be null) referencing A. For performance reasons I also want table C to have the same foreign key reference to table A. The constraint on table C should be that C must reference its parent (B) and also have the same foreign key reference to A as its parent. Anyone have any thoughts on how to do this?

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