common-table-expression

问题 I am trying to understand the concepts of using CTE in my SQL code. I have gone through a number of online posts explaining the concept but I cannot grasp how it iterates to present the hierarchical data. One of the widely used examples to explain the R-CTE is the Employee and ManagerID Example as below: USE AdventureWorks GO WITH Emp_CTE AS ( SELECT EmployeeID, ContactID, LoginID, ManagerID, Title, BirthDate FROM HumanResources.Employee WHERE ManagerID IS NULL UNION ALL SELECT e.EmployeeID,

问题 I am trying to understand the concepts of using CTE in my SQL code. I have gone through a number of online posts explaining the concept but I cannot grasp how it iterates to present the hierarchical data. One of the widely used examples to explain the R-CTE is the Employee and ManagerID Example as below: USE AdventureWorks GO WITH Emp_CTE AS ( SELECT EmployeeID, ContactID, LoginID, ManagerID, Title, BirthDate FROM HumanResources.Employee WHERE ManagerID IS NULL UNION ALL SELECT e.EmployeeID,

问题 I am trying to use "WITH" that is Common Table Expression within the function of PostgreSQL. Here is the following example: Example : Create or replace function withFunction() returns void as $Body$ Begin WITH cmn_l1 AS ( SELECT "PhoneNumber1","PhoneNumber2", DENSE_RANK() OVER(Partition by "PhoneNumber1" Order By "PhoneNumber2" )FoundIn From tablename; ) SELECT DISTINCT * INTO temptable FROM cmn_l1 WHERE FoundIn > 1; end; $Body$ language plpgsql; Question : How to execute and get values into

问题 Can anyone help me understand how this recursive CTE works? WITH RECURSIVECTE (EMPID, FULLNAME, MANAGERID, [ORGLEVEL]) AS (SELECT EMPID, FULLNAME, MANAGERID, 1 FROM RECURSIVETBL WHERE MANAGERID IS NULL UNION ALL SELECT A.EMPID, A.FULLNAME, A.MANAGERID, B.[ORGLEVEL] + 1 FROM RECURSIVETBL A JOIN RECURSIVECTE B ON A.MANAGERID = B.EMPID) SELECT * FROM RECURSIVECTE; 回答1: Recursive CTEs in SQL Server have 2 parts: The Anchor : Is the starting point of your recursion. It's a set that will be further

问题 Given below is a sample of my two different query execution with same result The select query using inner-select . select p.product from ( select * from tbl_a where productid not in (select productid from tbl_b) ) p order by p.product And select query using CTE . with cte as ( select * from tbl_a where productid not in (select productid from tbl_b) ) select product from cte order by product So my question is which among the above is good to use? And At what condition can use each of them? 回答1

问题 Right now I am running a query to find and replace a dynamic word within a document into a link. It works just fine but returns null when there are some special characters. Currently I am having issues with the dynamic word contains an ampersand '&' Here is part of the content: <p>STEPS:</p> <p> <p>Please refer to <|Cease & Desist|> policy.</p> It is returning a NULL for 'Cease & Desist' Below is the code I am using, what I need is for it to return the entire dynamic word even if it contains

问题 Is there a way to force Greenplum PostgreSQL to materialize a subquery in a WITH clause like what MATERIALIZE and INLINE optimizer hints do as below in Oracle? WITH dept_count AS ( SELECT /*+ MATERIALIZE */ deptno, COUNT(*) AS dept_count FROM emp GROUP BY deptno) SELECT ... I've been searching this for a while, only to find this functionality in Oracle. I know I can use CREATE TABLE AS , but I have several similar queries, forcing me to drop the temporary table after each query, which is very

问题 Is there a way to force Greenplum PostgreSQL to materialize a subquery in a WITH clause like what MATERIALIZE and INLINE optimizer hints do as below in Oracle? WITH dept_count AS ( SELECT /*+ MATERIALIZE */ deptno, COUNT(*) AS dept_count FROM emp GROUP BY deptno) SELECT ... I've been searching this for a while, only to find this functionality in Oracle. I know I can use CREATE TABLE AS , but I have several similar queries, forcing me to drop the temporary table after each query, which is very

问题 Closed . This question needs details or clarity. It is not currently accepting answers. Want to improve this question? Add details and clarify the problem by editing this post. Closed 2 years ago . I am using a cte in stored procedure. I have to use it multiple times ie populate cte for different ids how can I drop or remove current cte thanks ;WITH PAYOUT_CTE(REGNKEY, REGNTPE) AS ( SELECT REG_KEY, 'Parent' FROM ML_MSTR_REGN A (NOLOCK) WHERE A.COMP_NO = @COMP_NO AND A.REG_KEY = @CUR_KEY UNION

问题 I need to update an existing table with data from another. My CTE is giving me correct result, but when I'm trying to update with the CTE SSMS complains on Msg 102, Level 15, State 1, Line 13 Incorrect syntax near '.'. or Invalid column names at the lines below: set cm.Action.Identifier_fk = ID set cm.ActionRequestedAction = Action set cm.Action.apartment_fk = apartment_fk This is the code: Use DB; GO with CTE (ID,Action,Identifier_fk,apartment_fk) AS (select a.ID, a.Action, b.Identifier_fk,