'CREATE FUNCTION' must be the first statement in a query batch. Entity Framework Code First

You can avoid the

should be the first statement in a batch file

error without adding GO statements by putting the sql inside an EXEC command:

Sql(EXEC('BEGIN CREATE FUNCTION etc'))

Reference:

https://stackoverflow.com/a/20352867/150342

You have to generate your code and execute it as dynamic sql.

DECLARE @Sql NVARCHAR(MAX)
SET @Sql = 
'
IF OBJECT_ID(''fn_Test'') IS NOT NULL DROP FUNCTION fn_Test
GO

CREATE FUNCTION fn_Test(@a INT)
RETURNS INT
BEGIN
    RETURN @a
END
'
IF 1 = 1
BEGIN
    EXEC(@Sql)
END