CAST and CONVERT in T-SQL

Question

Is it posible to CAST or CONVERT with string data type (method that takes data type parametar as string), something like:

CAST('11' AS 'int') 

but not

CAST('11' AS int)

Answer 1

No. There are many places in T-SQL where it wants, specifically, a name given to it - not a string, nor a variable containing a name.

Answer 2

If you want to use dynamic sql, this should get you started:

DECLARE @datatype varchar(20)
DECLARE @sql varchar(4000)

SELECT @datatype = 'int'

SELECT @sql = 'PRINT CAST(''11'' AS '+@datatype+')'

exec (@sql)

Depending on what you exactly want/need you should read The Curse and Blessings of Dynamic SQL, especially the parts about sp_executesql