I would like to come up with a standard practice to prevent any tables from having duplicates where it matters. In most cases duplicates are a combination of variables rather than one. My primary keys are just the unique ids for each field so I cannot use them. What I have been doing is querying the table first and then if the number of rows for the combination in question is 0, making the insert. However, I have read it should be possible to set up a unique key over multiple fields to enforce uniqueness. INSERT IGNORE sounds like a good possibility, however, I would need it to ignore on more than one column.
As an example, with the fields followers and followed, there can be multiple followers and followeds in a table but should only be one combination of both.
Can anyone suggest syntax first to create the unique keys over multiple fields and then to do a SQL insert query that prevents dupes? Many thanks.