Invalid use of a side-effecting operator 'INSERT' within a function - Multiple Inserts in Function

Question

If this is not the right forum please let me know and move it for me.

I've just got a bunch of inserts like this toward the end of my scalar function:

   INSERT INTO [Raptor].[dbo].[UserRole]
           ([RoleId]
           ,[UserId])
     VALUES
           (3
           ,@NewUserID)

    INSERT INTO [Raptor].[dbo].[UserRole]
               ([RoleId]
               ,[UserId])
         VALUES
               (5
               ,@NewUserID)

Answer 1

In T-SQL, you cannot modify any data in a function. There is no straightforward way around it. There are some obscure hacks, but I would not use them. Use a stored procedure.

The hack, quoting from Erland Sommarskog:

CREATE FUNCTION loophole(@i int) RETURNS varchar(20) AS
  BEGIN
     DECLARE @sql varchar(MAX),
             @cmd varchar(4000)
     SELECT @sql = ' UPDATE rsci ' +
                   ' SET b = CASE ' + ltrim(str(@i + 1)) +
                   ' WHEN 1 THEN ''Ett'' WHEN 2 THEN ''Två''' +
                   ' WHEN 3 THEN ''Tre'' WHEN 4 THEN ''Fyra''' +
                   ' WHEN 5 THEN ''Fem'' WHEN 6 THEN ''Sex''' +
                   ' WHEN 7 THEN ''Sju'' WHEN 8 THEN ''Åtta''' +
                   ' WHEN 9 THEN ''Nio'' WHEN 10 THEN ''Tio'' END' +
                   ' WHERE a = ' + ltrim(str(@i + 1))
     SELECT @cmd = 'sqlcmd -S ' + @@servername + ' -d ' + db_name() +
                   ' -Q "' + @sql + '"'
     EXEC master..xp_cmdshell @cmd, 'no_output'
     RETURN (SELECT b FROM rsci WHERE a = @i)
  END

Answer 2

There is an exception (I'm using SQL 2014) when you are only using Insert/Update/Delete on Declared-Tables. These Insert/Update/Delete statements cannot contain an OUTPUT statement. The other restriction is that you are not allowed to do a MERGE, even into a Declared-Table. I broke up my Merge statements, that didn't work, into Insert/Update/Delete statements that did work.

The reason I didn't convert it to a stored-procedure is that the table-function was faster (even without the MERGE) than the stored-procedure. This is despite the stored-procedure allowing me to use Temp-Tables that have statistics. I needed the table-function to be very fast, since it is called 20-K times/day. This table function never updates the database.

I also noticed that the NewId() and RAND() SQL functions are not allowed in a function.