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There are two disadvantages involved with this: LEFT JOIN CTEPER ON CTESTUD2.SID = CTEPER.P_Id LEFT JOIN CTESTUD2 ON CTESTUD1.SID = CTESTUD2.SID SELECT CTESTUD1.SID, Name, Address, Cell_No, City, State Now, if I want to retrieve all the details from these three tables about all the name of the students from the Students1 table, then write the query like this: WITH CTESTUD1ĪS (SELECT SID,Name,City,State FROM Students1),ĪS (SELECT P_Id,Address,M_Id FROM Persons)
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This will become clearer, if you follow up the example:įor this, we will also have to include the third table Persons Suppose, if want to retrieve data from multiple tables, then it’s better to use CTE with multiple references.
![sql server cte sql server cte](https://i1.wp.com/sqlskull.com/wp-content/uploads/2020/01/CTE.png)
Like it is being called in the WHERE clause here, because we need to retrieve the Names of Students1 table, where SID is being equal to CTE1: WITH CTE1 (SID)ĪS (SELECT SID FROM Students2 WHERE Name = 'Robin') So, the CTE1 can be called anywhere in the outer query where it needs. Now, we will create a CTE named as ‘CTE1’ which will select SID column from Students2 table. I have two tables Students1 and Students2. The following example will make you understand what actually is the CTE.This is why the statement before a CTE must be terminated with a semicolon. The WITH keyword not only begins a CTE, it also adds a hint to a table reference.This can be used to give the alias to the retrieve field of the CTE. The name is mandatory and the argument is an optional. Here the Select statement must be very next to the CTE.The CTE uses the WITH clause, so the syntax can be shown as:.CTE’s can also recursively refer to the same table using a union or union all, and this works great for searching an adjacency pairs pattern hierarchy.It can be used instead of temp table or table variables in the stored procedures in the circumstances.The CTE’s can be used and compiled in exactly the same ways that simple Subqueries are being used.The CTE defines about a temporary view, which can be referenced in the same query just as a view.The Common Table Expression (CTE) was introduced earlier in the SQL Server 2005.If you don’t know much about it, then don’t worry at all.