Given the following table in SQL Server 2005:
ID Col1 Col2 Col3 -- ---- ---- ---- 1 3 34 76 2 32 976 24 3 7
Using CROSS APPLY:
CROSS APPLY
SELECT ID, Col1, Col2, Col3, MinValue FROM YourTable CROSS APPLY (SELECT MIN(d) AS MinValue FROM (VALUES (Col1), (Col2), (Col3)) AS a(d)) A
SQL Fiddle