How do I perform an IF...THEN
in an SQL SELECT
statement?
For example:
SELECT IF(Obsolete = 'N' OR InStock = 'Y' ? 1 : 0) AS Saleable, * FROM Product
Any T-SQL statement can be executed conditionally using IF… ELSE. If the condition evaluates to True, then T-SQL statements followed by IF condition in SQL server will be executed. If the condition evaluates to False, then T-SQL statements followed by ELSE keyword will be executed.
It is like a Shorthand form of CASE statement. We can conveniently use it when we need to decide between two options. There are three parts in IIF statement, first is a condition, second is a value if the condition is true and the last part is a value if the condition is false.
The CASE
statement is the closest to IF in SQL and is supported on all versions of SQL Server.
SELECT CAST( CASE WHEN Obsolete = 'N' or InStock = 'Y' THEN 1 ELSE 0 END AS bit) as Saleable, * FROM Product
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 Obsolete = 'N' or InStock = 'Y' THEN 1 ELSE 0 END as Saleable, * FROM Product
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(Obsolete = 'N' or InStock = 'Y', 1, 0) as Saleable, * FROM Product
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