Re: adding forign key

[Diego Mitch]

I dont know if it is your case, but i found a similar problem when:

I HAD THREE TABLES:
1) MARK (COLUMNS = MARKCODE, MARKNAME)
2) MODELS (COLUMNS = MARKCODE, MODELCODE, MODELNAME)
3) TRANSACTIONS. (COLUMNS = NUMBERTRANSACTION, MARKCODE, MODELCODE, QUANTITY)

MODELS HAD A FOREIGN KEY (MARKCODE) POINTING TO MARK

I TRIED TO ADD TWO FOREIGN KEYS (MARKCODE AND MODELCODE) TO TRANSACTIONS POINTING TO MARK AND MODELS. I COULDNT WHY?

SIMPLE BECAUSE I HAD ALREADY USED THE TABLE TRANSACTIONS AND COPY IN IT SOME VALUES OF MARKCODE AND MODELCODE, THAT AFTERWARDS THEY WERE ALREADY DELETED IN THE MARK TABLE AND MODEL TABLE SO THE FOREIGN KEY IN THESE ROWS COULD NOT MATCH ANY VALUE IN THE OTHER TWO TABLES.