Specifying Column Name As A Parameter in SELECT statement?

Question

I need to do something like this, but it always fails with \'Error converting data type varchar to int\':

DECLARE @intParam INT
DECLARE @ColName VARCHAR(64)
         


        

Answer 1

You need to use dynamic sql:

• build your dynamic SQL query (take a look at @SQL variable in sample below)
• use output parameter to get value back from dynamic sql (take a look at @intParam and @intParam_out in sample below)
• execute dynamic sql using sp_executesql

DECLARE @intParam INT
DECLARE @ColName VARCHAR(64)

SET @ColName='intcolumn'

DECLARE @SQL NVARCHAR(1000)
SET @SQL = 'SELECT @intParam_out = ' + @ColName + ' FROM myTable'
exec sp_executesql @SQL, N'@intParam_out int OUTPUT', @intParam_out = @intParam OUTPUT

Answer 2

Use Cast:

SET @intParam = SELECT cast(@ColName as int) FROM myTable