sql server 2008 - SQL TRIGGER THE MULTI-PART IDENTIFIER CANT BE BOUND -

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i new programming. trying teach myself sql. made video store database customer, rental, , inventory table. looking @ examples online try learn sql, please kind. want trigger stop person renting same movie @ same time. have been reading on triggers , code below.

i getting syntax errors on last end, syntax error on raiseerror, , inserted. still getting message "trigger multipart identifier cannot bound" on i.rental.rentnum inserted i;

any appreciated!

create trigger insteadofinsert on rental instead of insert declare @rentnum int, @action varchar(60)   select @rent_rentnum=i.rental.rentnum inserted i; set  @action='stop rental trigger.'      @rent_rentnum=(select rentnum inserted;   begin    begin tran      set nocount on        if (@rent_rentnum=rental.rentnum)          begin             raiseerror ('you cannot rent same move twice');            rollback          end        else          begin            insert            rental(rentnum)                   values                 (@rentnum)            insert                rent values (rentnum);            commit            print 'updated'         end        end

your trigger has several fundamental flaws:

  • please never ever use begin tran inside trigger! trigger running in context of statement caused fire, , therefore already in context of transaction

  • you need aware trigger called once per statement - not once per row! if insert statement inserts 10 rows, trigger fired once, , inserted pseudo table contain 10 rows of data - 1 think picked in statement

    select rentnum inserted;

    one of them - 1 more or less @ random - , 9 others ignored.

so basically, need totally rewrite trigger this:

create trigger insteadofinsert  on dbo.rental after insert     // if 1 of rows inserted exists in rental table -> abort     if exists (select * dbo.rental rentnum in (select rentnum inserted))     begin                 raiseerror ('you cannot rent same move twice');         rollback     end

you didn't explain why had picked use instead of insert trigger - don't see reason that, chose after insert trigger instead (it's plain simpler write these)


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