Question

I have two tables. Those tables have two relation between them.

Table 1    * ID_XPTO (PK)    * Detail  Table 2    * ID_XPTO (FK) (PK)    * ID_XPTO2 (FK) (PK) 

Those two relations exists.

Table 1 -< Table2  Table 1 -< Table2 

My question is that I need to delete some row in table 1. I’m currently doing,

declare @table Table (xptoTable2 int) insert into @table         select ID_XPTO2         from Table2          where ID_XPTO = @ID_XPTO  delete from Table2 where ID_XPTO = @ID_XPTO  delete from Table where ID_XPTO in (select xptoTable2from @table) 

I know that I could use ON DELETE SET NULL on table2. On that way I could then search for all rows with null value on ID_XPTO2 and delete them, but DBA does not wants to use it.

Is there some better solution to do this process?

Answer 1

You have these options:

• Delete in two statements, as you are doing now. Delete from Table2 first.

• Delete from two tables in one statement, if your brand of database supports multi-table DELETE syntax (e.g. MySQL). This is not standard SQL, but it is handy.

• Use cascading referential integrity constraints (I understand your DBA has nixed this option).

• Write a trigger BEFORE DELETE on Table1, to delete or set NULL any reference in Table2. Check with your DBA to see if this is any more acceptable than the cascading RI constraints.

Finally, I would advise talking to your DBA and asking the same question you asked here. Find out what solution he/she would prefer you to use. Folks on StackOverflow can answer technical questions, but it sounds like you are dealing with an IT policy question.