Create trigger for “before insert”

Question

I want to make a trigger for one table that will be used before INSERT.

I want to check if two columns are NULL and if they are NULL raise an e

Answer 1

Use instead trigger and inserted table like below and have a try.

CREATE TRIGGER INS_TABLE_1
ON mytable
INSTEAD OF INSERT
AS
BEGIN
    DECLARE @fn varchar(50),@ln varchar(50)
    SELECT @fn=column1 ,@ln=column12 from inserted
    IF (@fn IS NULL OR @ln IS NULL)
    BEGIN
        RAISERROR ('You are not allowed to Add These Data.', 10, 11)
    END
    ELSE
        INSERT INTO mytable (column1 ,column2) values (@fn,@ln)
END

The inserted table stores copies of the affected rows during INSERT and UPDATEstatements. Instead of trigger replaces the current INSERT by the trigger definition.