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• SQL SERVER – CTE can be Updated

  - by Pinal Dave

  Today I have received a fantastic email from Matthew Spieth. SQL Server expert from Ohio. He recently had a great conversation with his colleagues in the office and wanted to make sure that everybody who reads this blog knows about this little feature which is commonly confused. Here is his statement and we will start our story with Matthew’s own statement: “Users often confuse CTE with Temp Table but technically they both are different, CTE are like Views and they can be updated just like views.“ Very true statement from Matthew. I totally agree with what he is saying. Just like him, I have enough, time came across a situation when developers think CTE is like temp table. When you update temp table, it remains in the scope of the temp table and it does not propagate it to the table based on which temp table is built. However, this is not the case when it is about CTE, when you update CTE, it updates underlying table just like view does. Here is the working example of the same built by Matthew to illustrate this behavior. Check the value in the base table first. USE AdventureWorks2012; -- Check - The value in the base table is updated SELECT Color FROM [Production].[Product] WHERE ProductNumber = 'CA-6738'; Now let us build CTE with the same data. ;WITH CTEUpd(ProductID, Name, ProductNumber, Color) AS( SELECT ProductID, Name, ProductNumber, Color FROM [Production].[Product] WHERE ProductNumber = 'CA-6738') Now let us update CTE with following code. -- Update CTE UPDATE CTEUpd SET Color = 'Rainbow'; Now let us check the BASE table based on which the CTE was built. -- Check - The value in the base table is updated SELECT Color FROM [Production].[Product] WHERE ProductNumber = 'CA-6738'; That’s it! You can update CTE and it will update the base table. Here is the script which you should execute all together. USE AdventureWorks2012; -- Check - The value in the base table is updated SELECT Color FROM [Production].[Product] WHERE ProductNumber = 'CA-6738'; -- Build CTE ;WITH CTEUpd(ProductID, Name, ProductNumber, Color) AS( SELECT ProductID, Name, ProductNumber, Color FROM [Production].[Product] WHERE ProductNumber = 'CA-6738') -- Update CTE UPDATE CTEUpd SET Color = 'Rainbow'; -- Check - The value in the base table is updated SELECT Color FROM [Production].[Product] WHERE ProductNumber = 'CA-6738'; If you are aware of such scenario, do let me know and I will post this on my blog with due credit to you. Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQL View, T SQL Tagged: CTE

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• CTE error: "Types don't match between the anchor and the recursive part"

  - by priyanka.sarkar

  I am executing ;with cte as ( select 1 as rn, 'name1' as nm union all select rn+1,nm = 'name' + CAST((rn+1) as varchar(255)) from cte a where rn<10) select * from cte and is receiving the error Msg 240, Level 16, State 1, Line 2 Types don't match between the anchor and the recursive part in column "nm" of recursive query "cte". Where I am making the mistake? Thanks in advance

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• SQL SERVER – Quiz and Video – Introduction to Hierarchical Query using a Recursive CTE

  - by pinaldave

  This blog post is inspired from SQL Queries Joes 2 Pros: SQL Query Techniques For Microsoft SQL Server 2008 – SQL Exam Prep Series 70-433 – Volume 2.[Amazon] | [Flipkart] | [Kindle] | [IndiaPlaza] This is follow up blog post of my earlier blog post on the same subject - SQL SERVER – Introduction to Hierarchical Query using a Recursive CTE – A Primer. In the article we discussed various basics terminology of the CTE. The article further covers following important concepts of common table expression. What is a Common Table Expression (CTE) Building a Recursive CTE Identify the Anchor and Recursive Query Add the Anchor and Recursive query to a CTE Add an expression to track hierarchical level Add a self-referencing INNER JOIN statement Above six are the most important concepts related to CTE and SQL Server.  There are many more things one has to learn but without beginners fundamentals one can’t learn the advanced  concepts. Let us have small quiz and check how many of you get the fundamentals right. Quiz 1) You have an employee table with the following data. EmpID FirstName LastName MgrID 1 David Kennson 11 2 Eric Bender 11 3 Lisa Kendall 4 4 David Lonning 11 5 John Marshbank 4 6 James Newton 3 7 Sally Smith NULL You need to write a recursive CTE that shows the EmpID, FirstName, LastName, MgrID, and employee level. The CEO should be listed at Level 1. All people who work for the CEO will be listed at Level 2. All of the people who work for those people will be listed at Level 3. Which CTE code will achieve this result? WITH EmpList AS (SELECT Boss.EmpID, Boss.FName, Boss.LName, Boss.MgrID, 1 AS Lvl FROM Employee AS Boss WHERE Boss.MgrID IS NULL UNION ALL SELECT E.EmpID, E.FirstName, E.LastName, E.MgrID, EmpList.Lvl + 1 FROM Employee AS E INNER JOIN EmpList ON E.MgrID = EmpList.EmpID) SELECT * FROM EmpList WITH EmpListAS (SELECT EmpID, FirstName, LastName, MgrID, 1 as Lvl FROM Employee WHERE MgrID IS NULL UNION ALL SELECT EmpID, FirstName, LastName, MgrID, 2 as Lvl ) SELECT * FROM BossList WITH EmpList AS (SELECT EmpID, FirstName, LastName, MgrID, 1 as Lvl FROM Employee WHERE MgrID is NOT NULL UNION SELECT EmpID, FirstName, LastName, MgrID, BossList.Lvl + 1 FROM Employee INNER JOIN EmpList BossList ON Employee.MgrID = BossList.EmpID) SELECT * FROM EmpList 2) You have a table named Employee. The EmployeeID of each employee’s manager is in the ManagerID column. You need to write a recursive query that produces a list of employees and their manager. The query must also include the employee’s level in the hierarchy. You write the following code segment: WITH EmployeeList (EmployeeID, FullName, ManagerName, Level) AS ( –PICK ANSWER CODE HERE ) SELECT EmployeeID, FullName, ” AS [ManagerID], 1 AS [Level] FROM Employee WHERE ManagerID IS NULL UNION ALL SELECT emp.EmployeeID, emp.FullName mgr.FullName, 1 + 1 AS [Level] FROM Employee emp JOIN Employee mgr ON emp.ManagerID = mgr.EmployeeId SELECT EmployeeID, FullName, ” AS [ManagerID], 1 AS [Level] FROM Employee WHERE ManagerID IS NULL UNION ALL SELECT emp.EmployeeID, emp.FullName, mgr.FullName, mgr.Level + 1 FROM EmployeeList mgr JOIN Employee emp ON emp.ManagerID = mgr.EmployeeId Now make sure that you write down all the answers on the piece of paper. Watch following video and read earlier article over here. If you want to change the answer you still have chance. Solution 1) 1 2) 2 Now compare let us check the answers and compare your answers to following answers. I am very confident you will get them correct. Available at USA: Amazon India: Flipkart | IndiaPlaza Volume: 1, 2, 3, 4, 5 Please leave your feedback in the comment area for the quiz and video. Did you know all the answers of the quiz? Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Joes 2 Pros, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• Inside Recursive CTE's

  A step by step explanation of how a recursive CTE actually works

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• SQL Azure and support for CTE syntax?

  - by Coolcoder

  Does anyone know if SQL Azure supports CTE syntax? Specifically; WITH, OVER, ROW_NUMBER(), PARTITION BY

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• CTE to build a list of departments and managers (hierarchical)

  - by Milky Joe

  I need to generate a list of users that are managers, or managers of managers, for company departments. I have two tables; one details the departments and one contains the manager hierarchy (simplified): CREATE TABLE [dbo].[Manager]( [ManagerId] [int], [ParentManagerId] [int]) CREATE TABLE [dbo].[Department]( [DepartmentId] [int], [ManagerId] [int]) Basically, I'm trying to build a CTE that will give me a list of DepartmentIds, together with all ManagerIds that are in the manager hierarchy for that department. So... Say Manager 1 is the Manager for Department 1, and Manager 2 is Manager 1's Manager, and Manager 3 is Manager 2's Manager, I'd like to see: DepartmentId, ManagerId 1, 1 1, 2 1, 3 Basically, managers are able to deal with all of their sub-manager's departments. Building the CTE to return the Manager hierarchy was fairly simple, but I'm struggling to inject the Departments in there: WITH DepartmentManagers AS ( SELECT ManagerId, ParentManagerId, 0 AS Depth From Manager UNION ALL SELECT Manager.ManagerId, Manager.ParentManagerId, DepartmentManagers.Depth + 1 AS Depth FROM Manager INNER JOIN DepartmentManagers ON DepartmentManagers.ManagerId = Manager.ParentManagerId ) Can anyone help?

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• Prevent recursive CTE visiting nodes multiple times

  - by bacar

  Consider the following simple DAG: 1->2->3->4 And a table, #bar, describing this (I'm using SQL Server 2005): parent_id child_id 1 2 2 3 3 4 //... other edges, not connected to the subgraph above Now imagine that I have some other arbitrary criteria that select the first and last edges, i.e. 1-2 and 3-4. I want to use these to find the rest of my graph. I can write a recursive CTE as follows (I'm using terminology from MSDN): with foo(parent_id,child_id) as ( // anchor member that happens to select first and last edges: select parent_id,child_id from #bar where parent_id in (1,3) union all // recursive member: select #bar.* from #bar join foo on #bar.parent_id = foo.child_id ) select parent_id,child_id from foo However, this results in edge 3-4 being selected twice: parent_id child_id 1 2 3 4 2 3 3 4 // 2nd appearance! How can I prevent the query from recursing into subgraphs that have already been described? I could achieve this if, in my "recursive member" part of the query, I could reference all data that has been retrieved by the recursive CTE so far (and supply a predicate indicating in the recursive member excluding nodes already visited). However, I think I can access data that was returned by the last iteration of the recursive member only. This will not scale well when there is a lot of such repetition. Is there a way of preventing this unnecessary additional recursion? Note that I could use "select distinct" in the last line of my statement to achieve the desired results, but this seems to be applied after all the (repeated) recursion is done, so I don't think this is an ideal solution. Edit - hainstech suggests stopping recursion by adding a predicate to exclude recursing down paths that were explicitly in the starting set, i.e. recurse only where foo.child_id not in (1,3). That works for the case above only because it simple - all the repeated sections begin within the anchor set of nodes. It doesn't solve the general case where they may not be. e.g., consider adding edges 1-4 and 4-5 to the above set. Edge 4-5 will be captured twice, even with the suggested predicate. :(

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• Recursive CTE Problem

  - by Chris

  Hi, I am trying to use a recursive CTE in SQL Server to build up a predicate formula from a table containing the underlying tree structure. For example, my table looks like: -------------------------- Id Operator/Val ParentId -------------------------- 1. 'OR' NULL 2. 'AND' 1 3. 'AND' 1 4. '' 2 5. 'a' 4 6. 'alpha' 4 : : : -------------------------- which represents ((a alpha) AND (b beta)) OR ((c gamma) AND (a < delta)). ParentId is a reference to the Id in the same table of the parent node. I want to write a query which will build up this string from the table. Is it possible? Thanks

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• SQL Server CTE referred in self joins slow

  - by Kharlos Dominguez

  Hello, I have written a table-valued UDF that starts by a CTE to return a subset of the rows from a large table. There are several joins in the CTE. A couple of inner and one left join to other tables, which don't contain a lot of rows. The CTE has a where clause that returns the rows within a date range, in order to return only the rows needed. I'm then referencing this CTE in 4 self left joins, in order to build subtotals using different criterias. The query is quite complex but here is a simplified pseudo-version of it WITH DataCTE as ( SELECT [columns] FROM table INNER JOIN table2 ON [...] INNER JOIN table3 ON [...] LEFT JOIN table3 ON [...] ) SELECT [aggregates_columns of each subset] FROM DataCTE Main LEFT JOIN DataCTE BananasSubset ON [...] AND Product = 'Bananas' AND Quality = 100 LEFT JOIN DataCTE DamagedBananasSubset ON [...] AND Product = 'Bananas' AND Quality < 20 LEFT JOIN DataCTE MangosSubset ON [...] GROUP BY [ I have the feeling that SQL Server gets confused and calls the CTE for each self join, which seems confirmed by looking at the execution plan, although I confess not being an expert at reading those. I would have assumed SQL Server to be smart enough to only perform the data retrieval from the CTE only once, rather than do it several times. I have tried the same approach but rather than using a CTE to get the subset of the data, I used the same select query as in the CTE, but made it output to a temp table instead. The version referring the CTE version takes 40 seconds. The version referring the temp table takes between 1 and 2 seconds. Why isn't SQL Server smart enough to keep the CTE results in memory? I like CTEs, especially in this case as my UDF is a table-valued one, so it allowed me to keep everything in a single statement. To use a temp table, I would need to write a multi-statement table valued UDF, which I find a slightly less elegant solution. Did some of you had this kind of performance issues with CTE, and if so, how did you get them sorted? Thanks, Kharlos

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• SQL Server CTE Basics

  The CTE was introduced into standard SQL in order to simplify various classes of SQL Queries for which a derived table just wasn't suitable. For some reason, it can be difficult to grasp the techniques of using it. Well, that's before Rob Sheldon explained it all so clearly for us.

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• SQL Server 2008 ContainsTable, CTE, and Paging

  - by David Murdoch

  I'd like to perform efficient paging using containstable. The following query selects the top 10 ranked results from my database using containstable when searching for a name (first or last) that begins with "Joh". DECLARE @Limit int; SET @Limit = 10; SELECT TOP @Limit c.ChildID, c.PersonID, c.DOB, c.Gender FROM [Person].[vFullName] AS v INNER JOIN CONTAINSTABLE( [Person].[vFullName], (FullName), IS ABOUT ( "Joh*" WEIGHT (.4), "Joh" WEIGHT (.6)) ) AS k3 ON v.PersonID = k3.[KEY] JOIN [Child].[Details] c ON c.PersonID = v.PersonID JOIN [Person].[Details] p ON p.PersonID = c.PersonID ORDER BY k3.RANK DESC, FullName ASC, p.Active DESC, c.ChildID ASC I'd like to combine it with the following CTE which returns the 10th-20th results ordered by ChildID (the primary key): DECLARE @Start int; DECLARE @Limit int; SET @Start = 10; SET @Limit = 10; WITH ChildEntities AS ( SELECT ROW_NUMBER() OVER (ORDER BY ChildID) AS Row, ChildID FROM Child.Details ) SELECT c.ChildID, c.PersonID, c.DOB, c.Gender FROM ChildEntities cte INNER JOIN Child.Details c ON cte.ChildID = c.ChildID WHERE cte.Row BETWEEN @Start+1 AND @Start+@Limit ORDER BY cte.Row ASC

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• Recursive CTE with alternating tables

  - by SOfanatic

  I've created a SQL fiddle here. Basically, I have 3 tables BaseTable, Files, and a LinkingTable. The Files table has 3 columns: PK, BaseTableId, RecursiveId (ChildId). What I want to do is find all the children given a BaseTableId (i.e., ParentId). The tricky part is that the way the children are found works like this: Take ParentId 1 and use that to look up a FileId in the Files table, then use that FileId to look for a ChildId in the LinkingTable, if that record exists then use the RecursiveId in the LinkingTable to look for the next FileId in the Files table and so on. This is my CTE so far: with CTE as ( select lt.FileId, lt.RecursiveId, 0 as [level], bt.BaseTableId from BaseTable bt join Files f on bt.BaseTableId = f.BaseTableId join LinkingTable lt on f.FileId = lt.FileId where bt.BaseTableId = @Id UNION ALL select rlt.FileId, rlt.RecursiveId, [level] + 1 as [level], CTE.BaseTableId from CTE --??? and this is where I get lost ... ) A correct output for BaseTableId = 1, should be: FileId|RecursiveId|level|BaseTableId 1 1 0 1 3 2 1 1 4 3 2 1

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• Apply a recursive CTE on grouped table rows (SQL server 2005).

  - by Evan V.

  Hi all, I have a table (ROOMUSAGE) containing the times people check in and out of rooms grouped by PERSONKEY and ROOMKEY. It looks like this: PERSONKEY | ROOMKEY | CHECKIN | CHECKOUT | ROW ---------------------------------------------------------------- 1 | 8 | 13-4-2010 10:00 | 13-4-2010 11:00 | 1 1 | 8 | 13-4-2010 08:00 | 13-4-2010 09:00 | 2 1 | 1 | 13-4-2010 15:00 | 13-4-2010 16:00 | 1 1 | 1 | 13-4-2010 14:00 | 13-4-2010 15:00 | 2 1 | 1 | 13-4-2010 13:00 | 13-4-2010 14:00 | 3 13 | 2 | 13-4-2010 15:00 | 13-4-2010 16:00 | 1 13 | 2 | 13-4-2010 15:00 | 13-4-2010 16:00 | 2 I want to select just the consecutive rows for each PERSONKEY, ROOMKEY grouping. So the desired resulting table is: PERSONKEY | ROOMKEY | CHECKIN | CHECKOUT | ROW ---------------------------------------------------------------- 1 | 8 | 13-4-2010 10:00 | 13-4-2010 11:00 | 1 1 | 1 | 13-4-2010 15:00 | 13-4-2010 16:00 | 1 1 | 1 | 13-4-2010 14:00 | 13-4-2010 15:00 | 2 1 | 1 | 13-4-2010 13:00 | 13-4-2010 14:00 | 3 13 | 2 | 13-4-2010 15:00 | 13-4-2010 16:00 | 1 I want to avoid using cursors so I thought I would use a recursive CTE. Here is what I came up with: ;with CTE (PERSONKEY, ROOMKEY, CHECKIN, CHECKOUT, ROW) as (select RU.PERSONKEY, RU.ROOMKEY, RU.CHECKIN, RU.CHECKOUT, RU.ROW from ROOMUSAGE RU where RU.ROW = 1 union all select RU.PERSONKEY, RU.ROOMKEY, RU.CHECKIN, RU.CHECKOUT, RU.ROW from ROOMUSAGE RU inner join CTE on RU.ROWNUM = CTE.ROWNUM + 1 where CTE.CHECKIN = RU.CHECKOUT and CTE.PERSONKEY = RU.PERSONKEY and CTE.ROOMKEY = RU.ROOMKEY) This worked OK for very small datasets (under 100 records) but it's unusable on large datasets. I'm thinking that I should somehow apply the cte recursevely on each PERSONKEY, ROOMKEY grouping on my ROOMUSAGE table but I am not sure how to do that. Any help would be much appreciated, Cheers!

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• Filling the missing gaps(Sql Server 2005) [Set based using recursive CTE]

  - by Thinking

  I have a table MissingData 1 10 NULL NULL 22 NULL The desired output will be MissingData 1 10 10 10 22 22 i.e. the nulls will be filled up by the previous value until a new value is appearing. I can solve this by using loop but my requirement is to solve it by CTE in which I am not so comfortable as of now. Thanks

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• if else within CTE ?

  - by stackoverflowuser

  I want to execute select statement within CTE based on a codition. something like below ;with CTE_AorB ( if(condition) select * from table_A else select * from table_B ), CTE_C as ( select * from CTE_AorB // processing is removed ) But i get error on this. Is it possible to have if else within CTEs? If not is there a work around Or a better approach. Thanks.

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• Updating records with their subordinates via CTE or subquery

  - by Mike Jolley

  Let's say I have a table with the following columns: Employees Table employeeID int employeeName varchar(50) managerID int totalOrganization int managerID is referential to employeeID. totalOrganization is currently 0 for all records. I'd like to update totalOrganization on each row to the total number of employees under them. So with the following records: employeeID employeeName managerID totalOrganization 1 John Cruz NULL 0 2 Mark Russell 1 0 3 Alice Johnson 1 0 4 Juan Valdez 3 0 The query should update the totalOrganizations to: employeeID employeeName managerID totalOrganization 1 John Cruz NULL 3 2 Mark Russell 1 0 3 Alice Johnson 1 1 4 Juan Valdez 3 0 I know I can get somewhat of an org. chart using the following CTE: WITH OrgChart (employeeID, employeeName,managerID,level) AS ( SELECT employeeID,employeeName,0 as managerID,0 AS Level FROM Employees WHERE managerID IS NULL UNION ALL SELECT Employees.employeeID,Employees.employeeName,Employees.managerID,Level + 1 FROM Employees INNER JOIN OrgChart ON Employees.managerID = OrgChart.employeeID ) SELECT employeeID,employeeName,managerID, level FROM OrgChart; Is there any way to update the Employees table using a stored procedure rather than building some routine outside of SQL to parse through the data?

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• Is this possible with Sql 2005 CTE?

  - by aenima1982

  I have been working on a query that will return a suggested start date for a manufacturing line based on due date and the number of minutes needed to complete the task. There is a calendar table(LINE_ID, CALENDAR_DATE, SCHEDULED_MINUTES) that displays per manufacturing line, the number of minutes scheduled for that day. Example: (Usually 3 shifts worth of time scheduled per day, no weekends but can vary) 1, 06/8/2010 00:00:00.000, 1440 1, 06/7/2010 00:00:00.000, 1440 1, 06/6/2010 00:00:00.000, 0 1, 06/5/2010 00:00:00.000, 0 1, 06/4/2010 00:00:00.000, 1440 In order to get the suggested start date, I need to start with the due date and iterate downward through the days until i have accumulated enough time to complete the task. My Question can something like this be done with CTE, or is this something that should be handled by a cursor. Or... am i just going about this the wrong way completely??

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• Query gives an unsorted result set when run from stored procedure using CTE

  - by irtizaur

  I am trying to create a paging query using CTE. It works fine when I execute it from Microsoft SQL Server Management Studio Query Editor. And the result set is perfectly sorted as I want. But when I modify it for a stored procedure it gives me a unsorted result and I don't have any clue why. Here is my Query, with items as ( select ROW_NUMBER() over (order by create_time desc) number , i.item_name item_name , i.create_time create_time , c.category_name category_name , i.category_id category_id from cb_item i, cb_category c where i.category_id = c.category_id and c.category_id = '4E5248FE-05DD-4D01-ABBB-80C6E3BA5CDA' ) select item_name , create_time , category_name , category_id from items where number between 1 and 25 And this is the Stored Procedure Version, create procedure ItemPage @category_id uniqueidentifier , @from int , @to int , @sortby nvarchar(50) as begin with items as ( select ROW_NUMBER() over (order by @sortby) number , i.item_name item_name , i.create_time create_time , c.category_name category_name , i.category_id category_id from cb_item i, cb_category c where i.category_id = c.category_id and c.category_id = @category_id ) select item_name , create_time , category_name , category_id from items where number between @from and @to end exec itempage '4E5248FE-05DD-4D01-ABBB-80C6E3BA5CDA' , 1, 25, 'create_time desc' The first one gives me sorted result but procedure gives me unsorted result. I don't know why?

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• Performance considerations for common SQL queries

  - by Jim Giercyk

  Originally posted on: http://geekswithblogs.net/NibblesAndBits/archive/2013/10/16/performance-considerations-for-common-sql-queries.aspxSQL offers many different methods to produce the same results.  There is a never-ending debate between SQL developers as to the “best way” or the “most efficient way” to render a result set.  Sometimes these disputes even come to blows….well, I am a lover, not a fighter, so I decided to collect some data that will prove which way is the best and most efficient.  For the queries below, I downloaded the test database from SQLSkills:  http://www.sqlskills.com/sql-server-resources/sql-server-demos/.  There isn’t a lot of data, but enough to prove my point: dbo.member has 10,000 records, and dbo.payment has 15,554.  Our result set contains 6,706 records. The following queries produce an identical result set; the result set contains aggregate payment information for each member who has made more than 1 payment from the dbo.payment table and the first and last name of the member from the dbo.member table.   /*************/ /* Sub Query  */ /*************/ SELECT  a.[Member Number] ,         m.lastname ,         m.firstname ,         a.[Number Of Payments] ,         a.[Average Payment] ,         a.[Total Paid] FROM    ( SELECT    member_no 'Member Number' ,                     AVG(payment_amt) 'Average Payment' ,                     SUM(payment_amt) 'Total Paid' ,                     COUNT(Payment_No) 'Number Of Payments'           FROM      dbo.payment           GROUP BY  member_no           HAVING    COUNT(Payment_No) > 1         ) a         JOIN dbo.member m ON a.[Member Number] = m.member_no         /***************/ /* Cross Apply  */ /***************/ SELECT  ca.[Member Number] ,         m.lastname ,         m.firstname ,         ca.[Number Of Payments] ,         ca.[Average Payment] ,         ca.[Total Paid] FROM    dbo.member m         CROSS APPLY ( SELECT    member_no 'Member Number' ,                                 AVG(payment_amt) 'Average Payment' ,                                 SUM(payment_amt) 'Total Paid' ,                                 COUNT(Payment_No) 'Number Of Payments'                       FROM      dbo.payment                       WHERE     member_no = m.member_no                       GROUP BY  member_no                       HAVING    COUNT(Payment_No) > 1                     ) ca /********/                    /* CTEs  */ /********/ ; WITH    Payments           AS ( SELECT   member_no 'Member Number' ,                         AVG(payment_amt) 'Average Payment' ,                         SUM(payment_amt) 'Total Paid' ,                         COUNT(Payment_No) 'Number Of Payments'                FROM     dbo.payment                GROUP BY member_no                HAVING   COUNT(Payment_No) > 1              ),         MemberInfo           AS ( SELECT   p.[Member Number] ,                         m.lastname ,                         m.firstname ,                         p.[Number Of Payments] ,                         p.[Average Payment] ,                         p.[Total Paid]                FROM     dbo.member m                         JOIN Payments p ON m.member_no = p.[Member Number]              )     SELECT  *     FROM    MemberInfo /************************/ /* SELECT with Grouping   */ /************************/ SELECT  p.member_no 'Member Number' ,         m.lastname ,         m.firstname ,         COUNT(Payment_No) 'Number Of Payments' ,         AVG(payment_amt) 'Average Payment' ,         SUM(payment_amt) 'Total Paid' FROM    dbo.payment p         JOIN dbo.member m ON m.member_no = p.member_no GROUP BY p.member_no ,         m.lastname ,         m.firstname HAVING  COUNT(Payment_No) > 1   We can see what is going on in SQL’s brain by looking at the execution plan.  The Execution Plan will demonstrate which steps and in what order SQL executes those steps, and what percentage of batch time each query takes.  SO….if I execute all 4 of these queries in a single batch, I will get an idea of the relative time SQL takes to execute them, and how it renders the Execution Plan.  We can settle this once and for all.  Here is what SQL did with these queries:   Not only did the queries take the same amount of time to execute, SQL generated the same Execution Plan for each of them.  Everybody is right…..I guess we can all finally go to lunch together!  But wait a second, I may not be a fighter, but I AM an instigator.     Let’s see how a table variable stacks up.  Here is the code I executed: /********************/ /*  Table Variable  */ /********************/ DECLARE @AggregateTable TABLE     (       member_no INT ,       AveragePayment MONEY ,       TotalPaid MONEY ,       NumberOfPayments MONEY     ) INSERT  @AggregateTable         SELECT  member_no 'Member Number' ,                 AVG(payment_amt) 'Average Payment' ,                 SUM(payment_amt) 'Total Paid' ,                 COUNT(Payment_No) 'Number Of Payments'         FROM    dbo.payment         GROUP BY member_no         HAVING  COUNT(Payment_No) > 1   SELECT  at.member_no 'Member Number' ,         m.lastname ,         m.firstname ,         at.NumberOfPayments 'Number Of Payments' ,         at.AveragePayment 'Average Payment' ,         at.TotalPaid 'Total Paid' FROM    @AggregateTable at         JOIN dbo.member m ON m.member_no = at.member_no In the interest of keeping things in groupings of 4, I removed the last query from the previous batch and added the table variable query.  Here’s what I got:     Since we first insert into the table variable, then we read from it, the Execution Plan renders 2 steps.  BUT, the combination of the 2 steps is only 22% of the batch.  It is actually faster than the other methods even though it is treated as 2 separate queries in the Execution Plan.  The argument I often hear against Table Variables is that SQL only estimates 1 row for the table size in the Execution Plan.  While this is true, the estimate does not come in to play until you read from the table variable.  In this case, the table variable had 6,706 rows, but it still outperformed the other queries.  People argue that table variables should only be used for hash or lookup tables.  The fact is, you have control of what you put IN to the variable, so as long as you keep it within reason, these results suggest that a table variable is a viable alternative to sub-queries. If anyone does volume testing on this theory, I would be interested in the results.  My suspicion is that there is a breaking point where efficiency goes down the tubes immediately, and it would be interesting to see where the threshold is. Coding SQL is a matter of style.  If you’ve been around since they introduced DB2, you were probably taught a little differently than a recent computer science graduate.  If you have a company standard, I strongly recommend you follow it.    If you do not have a standard, generally speaking, there is no right or wrong answer when talking about the efficiency of these types of queries, and certainly no hard-and-fast rule.  Volume and infrastructure will dictate a lot when it comes to performance, so your results may vary in your environment.  Download the database and try it!

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• PowerPivot and Parent/Child hierarchies

  - by AlbertoFerrari

  Does PowerPivot handle Parent/Child hierarchies? The common answer is “no”, since it does not handle them natively. During last PowerPivot course in London, I have been asked the same question once more and had an interesting discussion about this severe limitation of the PowerPivot data modeling and visualization capabilities. On my way back in Italy, I started thinking at a possible solution and, after some work, I managed to make PowerPivot handle Parent/Child hierarchies in a very nice way, which...(read more)

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• CTE Join query issues

  - by Lee_McIntosh

  Hi everyone, this problem has me head going round in circles at the moment and i wondering if anyone could give any pointers as to where im going wrong. Im trying to produce a SPROC that produces a dataset to be called by SSRS for graphs spanning the last 6 months. The data for example purposes uses three tables (theres more but the it wont change the issue at hand) and are as follows: tbl_ReportList: Report Site ---------------- North abc North def East bbb East ccc East ddd South poa South pob South poc South pod West xyz tbl_TicketsRaisedThisMonth: Date Site Type NoOfTickets --------------------------------------------------------- 2010-07-01 00:00:00.000 abc Support 101 2010-07-01 00:00:00.000 abc Complaint 21 2010-07-01 00:00:00.000 def Support 6 ... 2010-12-01 00:00:00.000 abc Support 93 2010-12-01 00:00:00.000 xyz Support 5 tbl_FeedBackRequests: Date Site NoOfFeedBackR ---------------------------------------------------------------- 2010-07-01 00:00:00.000 abc 101 2010-07-01 00:00:00.000 def 11 ... 2010-12-01 00:00:00.000 abc 63 2010-12-01 00:00:00.000 xyz 4 I'm using CTE's to simplify the code, which is as follows: DECLARE @ReportName VarChar(200) SET @ReportName = 'North'; WITH TicketsRaisedThisMonth AS ( SELECT [Date], Site, SUM(NoOfTickets) AS NoOfTickets FROM tbl_TicketsRaisedThisMonth WHERE [Date] >= DATEADD(mm, DATEDIFF(m,0,GETDATE())-6,0) GROUP BY [Date], Site ), FeedBackRequests AS ( SELECT [Date], Site, SUM(NoOfFeedBackR) AS NoOfFeedBackR FROM tbl_FeedBackRequests WHERE [Date] >= DATEADD(mm, DATEDIFF(m,0,GETDATE())-6,0) GROUP BY [Date], Site ), SELECT trtm.[Date] SUM(trtm.NoOfTickets) AS NoOfTickets, SUM(fbr.NoOfFeedBackR) AS NoOfFeedBackR, FROM Reports rpts LEFT OUTER JOIN TotalIncidentsDuringMonth trtm ON rpts.Site = trtm.Site LEFT OUTER JOIN LoggedComplaints fbr ON rpts.Site = fbr.Site WHERE rpts.report = @ReportName GROUP BY trtm.[Date] And the output when the sproc is pass a parameter such as 'North' to be as follows: Date NoOfTickets NoOfFeedBackR ----------------------------------------------------------------------------------- 2010-07-01 00:00:00.000 128 112 2010-08-01 00:00:00.000 <data for that month> <data for that month> 2010-09-01 00:00:00.000 <data for that month> <data for that month> 2010-10-01 00:00:00.000 <data for that month> <data for that month> 2010-11-01 00:00:00.000 <data for that month> <data for that month> 2010-12-01 00:00:00.000 122 63 The issue I'm having is that when i execute the query I'm given a repeated list of values of each month, such as 128 will repeat 6 times then another value for the next months value repeated 6 times, etc. argh!

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• MS SQL server and Trees

  - by Julian

  Im looking for some way of extrating data form a tree table as defined below. Table Tree Defined as :- TreeID uniqueidentifier TreeParent uniqueidentifier TreeCode varchar(50) TreeDesc varchar(100) Data some (23k rows), Parent Refs back into ID in table The following SQL renders the whole tree (takes arround 2 mins 30) I need to do the following. 1) Render each Tree Node with its LVL 1 parent 2) Render all nodes that have a Description that matches a TreeDesc like 'SomeText%' 3) Render all parent nodes that are for a single tree id. Items 2 and 3 take 2mins30 so this needs to be a lot faster! Item 1, just cant work out how to do it with out killing SQL or taking forever any sugestions would be helpfull Thanks Julian WITH TreeCTE(TreeCode, TreeDesc, depth, TreeParent, TreeID) AS ( -- anchor member SELECT cast('' as varchar(50)) as TreeCode , cast('Trees' as varchar(100)) as TreeDesc, cast('0' as Integer) as depth, cast('00000000-0000-0000-0000-000000000000' as uniqueidentifier) as TreeParent, cast('00000000-0000-0000-0000-000000000000' as uniqueidentifier) as TreeID UNION ALL -- recursive member SELECT s.TreeCode, s.TreeDesc, cte.depth+1, isnull(s.TreeParent, cast('00000000-0000-0000-0000-000000000000' as uniqueidentifier)), isnull(s.TreeID, cast('00000000-0000-0000-0000-000000000000' as uniqueidentifier)) FROM pdTrees AS S JOIN TreeCTE AS cte ON isnull(s.TreeParent, cast('00000000-0000-0000-0000-000000000000' as uniqueidentifier)) = isnull( cte.TreeID , cast('00000000-0000-0000-0000-000000000000' as uniqueidentifier)) ) -- outer query SELECT s.TreeID, s.TreeCode, s.TreeDesc, s.depth, s.TreeParent FROM TreeCTE s

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• CTE and last known date processing

  - by stackoverflowuser

  Input @StartDate = '01/25/2010' @EndDate = '02/06/2010' I have 2 CTEs in a stored procedure as follows: with CTE_A as ( [gives output A..Shown below] ), with CTE_B as ( Here, I want to check if @StartDate is NOT in output A then replace it with the last known date. In this case, since @startdate is less than any date in output A hence @StartDate will become 02/01/2010. Also to check if @EndDate is NOT in output A then replace it with the last known date. In this case, since @enddate is 02/06/2010 hence it will be replace with 02/05/2010. // Here there is a query using @startDate and @EndDate. ) output A Name Date A 02/01/2010 B 02/01/2010 C 02/05/2010 D 02/10/2010

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• Need help with a SQL CTE Query

  - by Chuck

  I have a table that I need to get some specific data from for a view. Here's the base table structure with some sample data: | UserID | ReportsToUserID | Org ID | ------------------------------------- | 1 | NULL | 1 | ------------------------------------- | 2 | 1 | 1 | ------------------------------------- | 3 | 2 | 1 | ------------------------------------- | 4 | 3 | 1 | ------------------------------------- The users will be entering reports and users can see the reports of users who report to them and any users who report to those users. Users who report to no one can see everything in their organization Given my sample data above, user 1 can see the reports of 2, 3, & 4; user 2 can see the reports of 3 & 4; and user 3 can see the reports of 4. For the view, I'd like to have the data returned as follows: | UserID | CanSeeUserID | OrgID | -------------------------------------------- | 1 | 2 | 1 | -------------------------------------------- | 1 | 3 | 1 | -------------------------------------------- | 1 | 4 | 1 | -------------------------------------------- | 2 | 3 | 1 | -------------------------------------------- etc... Below is my current code, any help is greatly appreciated. WITH CTEUsers (UserID, CanSeeUserID, OrgID) AS ( SELECT e.ID, e.ReportsToUserID, e.OrgID FROM Users e WITH(NOLOCK) WHERE COALESCE(ReportsToUserID,0) = 0 --ReportsToUserID can be NULL or 0 UNION ALL SELECT e.ReportsToUserID, e.ID,e.OrgID FROM Users e WITH(NOLOCK) JOIN CTEUsers c ON e.ID = c.UserID ) SELECT * FROM CTEUsers

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• Recursive query using CTE

  - by Rohit Kandhal

  Need help for this .

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