   [web] SQL -  avoid duplicates in a table
  This is a SQL question.  I'm using MySQL.I want to be able to insert two values (a, b) in one row in a table, but only if these two values do not already exists in the same row in the exact columns.  How would I be able to create a stored function so that I don't create duplicates in the table?  I do not want these two columns to be unique because they won't be.Thanks in advance.   
Sounds to me like the 2 columns together are unique, so you can assign a primary key that spans the 2 columns (right?). The other way is just to check manually using an other select statement..Edo   ;  Create(a) a key comprised of those columns that need to be unique.or (b) an unique index comprised of the columns if there is already    a key defined.!!! DO NOT MESS UP YOUR DATABASE WITH TRIGGERS OR MANUAL VERIFICATION !!!   ;  Yeah, I forgot to mention that I already had another column as a primary key.  I looked up indexes and it was a good solution.  Thanks for your help.   