Search Postgresql Archives

Re: M:M table conditional delete for parents

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



I think a foreign key restraint is basically a trigger that throws an exception (RAISE statement) when the restraint is violated.

Something trigger function like:

     If table1
         if not in table1
              raise
     else if table2
         if not in table2
              raise
      end
I think that should work, but I've never tried it.


MargaretGillon@xxxxxxxxxxxxxx wrote:

Postgresql 8.1.4 on Redhat 9

I have a table which stores M:M relationships. I can't put foreign keys to the parents of this table because the relationships being stored go to several tables. This was done so that only two fields have to be searched in order for all relationships to be found for an item. For an oem number there might be 50 to 100 relationships and 40 different tables having to do with materials, locations, revisions, specifications, customer, etc. that might be referenced.

Is there some way I can make a mock foreign key restraint on the parents so the parent would search the M:M table for a matching value in key1 if the relate-key is 22, 23, 25 or 100 before it allows the row to be deleted?

relate-key relate-type key1 table1 key2 table2 22 product-material 23 oem 545 material 22 product-material 23 oem 546 material 23 product-engine 23 oem 15 engine 25 product-stage 23 oem 3 stage 100 product-revision 23 oem 2270 specifications


*** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
Margaret Gillon, IS Dept., Chromalloy Los Angeles



[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Index of Archives]     [Postgresql Jobs]     [Postgresql Admin]     [Postgresql Performance]     [Linux Clusters]     [PHP Home]     [PHP on Windows]     [Kernel Newbies]     [PHP Classes]     [PHP Books]     [PHP Databases]     [Postgresql & PHP]     [Yosemite]
  Powered by Linux