I'm looking for a way to build case statements in a sql select query using less than and greater than signs. For example, I want to select a ranking based on a variable:
DECLARE @a INT
SET @a = 0
SELECT CASE
WHEN @a < 3 THEN 0
WHEN @a = 3 THEN 1
WHEN @a > 3 THEN 2
END
I'd like to write it as:
DECLARE @a INT
SET @a = 0
SELECT CASE @a
WHEN < 3 THEN 0
WHEN 3 THEN 1
WHEN > 3 THEN 2
END
...but SQL doesn't let me use the < and > signs in this way. Is there a way that I can do this is SQL 2005, or do I need to use the code like in the first one.
The reason for only wanting the code there once is because it would make the code a lot more readable/maintainable and also because I'm not sure if SQL server will have to run the calculation for each CASE statement.
I'm looking for a VB.NET case statement equivelent:
Select Case i
Case Is < 100
p = 1
Case Is >= 100
p = 2
End Select
Maybe it's not possible in SQL and that's ok, I just want to confirm that.
You can use the SIGN function as
DECLARE @a INT
SET @a = 0
SELECT CASE SIGN(@a - 3)
WHEN -1 THEN 0
WHEN 0 THEN 1
WHEN 1 THEN 2
END
If @a
is smaller than 3, then @a - 3
results in a negative int, in which SIGN returns -1.
If @a
is 3 or greater, then SIGN returns 0 or 1, respectively.
If the output you want is 0, 1 and 2, then you can simplify even more:
DECLARE @a INT
SET @a = 0
SELECT SIGN(@a - 3) + 1
Using SIGN
as suggested by @Jose Rui Santos seems a nice workaround. An alternative could be to assign the expression an alias, use a subselect and test the expression (using its alias) in the outer select:
SELECT
…,
CASE
WHEN expr < 3 THEN …
WHEN expr > 3 THEN …
END AS …
FROM (
SELECT
…,
a complex expression AS expr
FROM …
…
)
SELECT
CASE
WHEN ColumnName >=1 and ColumnName <=1 THEN 'Fail'
WHEN ColumnName >=6 THEN 'Pass'
ELSE 'Test'
END
FROM TableName
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