Results 1 to 4 of 4
  1. #1

    Default MySql on delete cascade concept?

    I am trying to figure out how cascade delete works. I know the general concept but not the specifics of it.

    I have 3 tables (a)||---|<(B)>o---||(C)

    Table A: Aid Tag

    Table B: Aid (f) Cid (F)

    Table C: Cid Other

    A row in table A must have at least one reference to table c or else it should be deleted. A row in table A is made only when Table C tries creating a tag that does not exist. If table C removes that tag and no other rows from table C reference that tag then the tag should be removed. If another row from table C references that tag then the tag should not be deleted.

    If I set Table B [Aid] to delete cascade would it: 1) If the tag from table A is deleted automatically remove any links in table B 2) I delete a row from table B belonging to tagz. There is another row in table B that references tagz. Would that deletion cause tagz to be deleted as well or would tagz remain so long as any row references it?

  2. #2

  3. #3

    Default

    If you have set up table B to delete cascade on the foreign key to table A then if a tag get's deleted the corresponding records in Table B will be deleted. Table B deletions will not affect table A since table A does not have any references or foreign keys into table B.

  4. #4

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
| Travel Forum|