CTE with insert and update in sql server 2008 [duplicate] - sql

Question

This question already has answers here:
How can I reuse a Common Table Expression
(2 answers)
Closed 8 years ago.
I am using SQL Server 2008 and I want to know if I can use CTE with insert and update together e.g. if one condition fails then insert else update.
With X As
(
Select COMP
From comp
)
IF EXISTS ( Select * From A Where A.COMP = X.COMP )
Insert Into A (COMP,comp1)
select X.COMP, #COMP1 from X
Else
Update A set comp1=#comp1
where comp= X.Comp
I have tried to use
With X As
(
Select COMP
From comp
)
Insert Into A (COMP,comp1)
select X.COMP, #COMP1 from X
With Y As
(
Select COMP
From comp
)
Update A set comp1=#comp1
join Y on comp= Y.Comp
But if it is a insert then it is inserting the record and also it is executing the Update block . Can you tell me how to avoid that with If statement.

Answer 1

As you can only use CTE once after it is declared, you cannot used it in both INSERT and UPDATE statements.
As you cannot use MERGE due to constraints out of your control, as you say, you can use a temporary table instead:
Select COMP
into #temp
From comp
IF EXISTS ( Select * From A Where A.COMP = #temp.COMP )
Insert Into A (COMP,comp1)
select #temp.COMP, #COMP1 from #temp
Else
Update A set comp1=#comp1 where comp= #temp.Comp

Answer 2

A WITH clause can only be used with a single SELECT, INSERT, UPDATE or DELETE statement. It cannot be used with an IF or any other statement. That you've already been told in comments.
The reason why your second attempt, where you are trying to use separate WITH clauses for INSERT and UPDATE, fails is probably because there is no semicolon at the end of the INSERT statement. The WITH keyword has multiple uses in Transact-SQL and sometimes it is expected in the middle of the statement while at other times it goes at the beginning. To avoid ambiguity, a semicolon is made mandatory (in SQL Server 2008 and later version) at the end of a statement if the next statement begins with a WITH clause.
But actually it would be a good idea to get into the habit of using semicolons anyway.
So, this is how you should run these two statements together:
With X As
(
Select COMP
From comp
)
Insert Into A (COMP,comp1)
select X.COMP, #COMP1 from X; /* <-- this semicolon is required */
With Y As
(
Select COMP
From comp
)
Update A set comp1=#comp1
join Y on comp= Y.Comp; /* <-- this one is optional,
but why not make things consistent? */