MySQL performance tip No. 3: Rows can be served from indexes InnoDB can find and actually serve rows directly from indexes, whereas a secondary key points to the primary key and the primary key ...

Any attribute that is uniquely identify a row in a table is candidate key (primary key) for the table. We select one of the candidate key as Primary key. All candidate keys which are not chosen as ...

Duplicate and Ignore on MySQL Inserts. MySQL table primary keys and unique indexes prevent multiple rows with the same index from being added to the table. If you try to insert a duplicate row ...