How do I perform an IF THEN statement in an SQL SELECT

Question

How to execute an IF...THEN in an SQL SELECT statement

For example:

SELECT IF(Accept = 'Y' OR Reject = 'N' ? 1 : 0) AS Approved, * FROM Sales

Answer 1

The CASE statement is the closest to IF in SQL and is supported on all versions of SQL Server.

SELECT CAST(
             CASE
                  WHEN Accept = 'Y' or Reject = 'N'
                     THEN 1
                  ELSE 0
             END AS bit) as Approved, *
FROM Sales

You only need to use the CAST operator if you want the result as a Boolean value. If you are happy with an int, this works:

SELECT CASE
            WHEN Accept = 'Y' or Reject = 'N'
               THEN 1
               ELSE 0
       END as Approved, *
FROM Sales

CASE statements can be embedded in other CASE statements and even included in aggregates.

SQL Server Denali (SQL Server 2012) adds the IIF statement which is also available in access (pointed out by Martin Smith):

SELECT IIF(Accept = 'Y' or Reject = 'N', 1, 0) as Approved, * FROM Sales