Thread: QUESTION: Automatically generating Primary keys !!!
**** Post for FREE via your newsreader at post.usenet.com **** Hello, I'm working on some sort of search-engine which is accesable by a browser. On of the features of the engine is that you can insert new data into it just by using your browser. For all this I use PHP, my database is in Postgresql. My problem is that I should be able to let the Database System (Postgresql) generate its own primairy keys (from the rest of the data). eg. I've got a table like this: workplace_ID, name, street, nr, zipcode, city, country workplace_ID is the primairy key of that table. Some other tables have a foreign key refering to it. As a primairy key this ID is of course unique. My Question is: How can I see which values (of the primairy key) are already taken, and which is available for new data. Thanks a lot STom -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= *** Usenet.com - The #1 Usenet Newsgroup Service on The Planet! *** http://www.usenet.com -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Tom Janssens wrote: > My problem is that I should be able to let the Database System (Postgresql) > generate its own primairy keys (from the rest of the data). > workplace_ID, name, street, nr, zipcode, city, country > > workplace_ID is the primairy key of that table. Some other tables have a > foreign key refering to it. As a primairy key this ID is of course unique. > My Question is: How can I see which values (of the primairy key) are already > taken, and which is available for new data. Other than with SELECT? If it's not too late, I'd make workplace_ID into a serial and let PostgreSQL generate the values for you. If it is too late, and workplace_id is text you could try appending nextval(some_seq) to the end of it - that would guarantee uniqueness. - Richardh