Hello, I have this situation: Table a has an id and a name field Table b has an id and a name field Table c has an id field, an external code field and a name field The external code field of table c must be an existing id in table a or in table b, thus it is a foreign key. I do know, for example, how to make the external code field from table c deppend on the id field of table b ... what I don't know is if it is possible to make it refer to the id field from table b or to the id field of table a. I know this would cause some ambiguity in a ondelete rule, but what I need is to guarantee that the external field from table c will accept only values present on table a or on table b. Do you know if this is possible and, if it is, how to do it in the mysql database? Sure I can implement this in the code but I was woundering if it is possible to build this kind of rule in the database. Thanks Marlon -- When you say "I wrote a program that crashed Windows," people just stare at you blankly and say "Hey, I got those with the system, for free." Linus Torvalds __________ View the list's information and change your settings at //www.freelists.org/list/programmingblind