SQL SERVER 2005如果是的话

Question

I am running following query.

SELECT T1.C1, T2.C2..., 
IF( T1.C1<>T2.C1,"Changed","1") AS NewColumn
From T1 INNER JOIN T2
Where condition..

I am getting syntax error for IF statement.

Motive is to compare columns from two different tables, if not equal save as "Changed" in NewColumn of third table.. This is a Insert INTO query .

T-> Table
C->Column

Answer 1

You have to use CASE WHEN in this context.

SELECT     T1.C1, 
           T2.C2..., 
           CASE WHEN T1.C1<>T2.C1 THEN 'Changed' ELSE '1' END AS NewColumn 
FROM       T1 
INNER JOIN T2 
WHERE      condition

Answer 2

SELECT T1.C1, T2.C2..., 
    CASE WHEN T1.C1<>T2.C1 THEN 'Changed' ELSE '1' END AS NewColumn 
From T1 INNER JOIN T2 ON ... 
Where ...

Answer 3

Others have already mentioned that you should use CASE WHEN ELSE END. The difference between the two is that IF changes the flow of execution of your code - you can conditionally execute code depending on the result of your IF statement. CASE doesn't change the execution flow - it simply lets you check a value, and then get a different result depending on the result.

Answer 4

When you want to use condition checks inside the statement, you should use CASE WHEN

MSDN

But if you have multiline statements, the you can use IF ELSE clause