> I have a primary key set on a table which consists of the combination of the > values: firstname, lastname, and a schedule_id (BIGINT(20))... I have this > so the records in this table do not have duplicates, being that no one > record should have the exact same name and schedule_id identifier. > > However, I want to keep this same restriction while also ensuring that no > two records have the same email_address and schedule_id identifier... > > You can't have the db enforce two different primary keys on one table, so > how would I implement having this kind of restriction, which, in itself, > seems to require that I have a second primary key to enforce another > constraint to dissalow records to be added that carry the same combination > of: email_address and schedule_id?
You cannot have multiple PRIMARY key constraints, that's why it's called "primary". You can, however, use multiple "unique constraints", which do (almost) the same. With regard to other replies: indices are used for quick data retrieval, constraints for business requirements. That there happens to be something as a "unique index" is an implementation artifact. Martijn Tonies Database Workbench - development tool for MySQL, and more! Upscene Productions http://www.upscene.com My thoughts: http://blog.upscene.com/martijn/ Database development questions? Check the forum! http://www.databasedevelopmentforum.com -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
