Foreign key

[ppp001]

Hi, for a database table having a foreign key refered to another table, what advantage will it gain to have the foreign key ? Will it faster in joining the refered and referring table ? or something else ? Thanks

[whizzs]

Typically they are used for inner joins to prevent cartesian products

[Andre Ziegler]

foreign keys are used for checking references between records in different tables. With a constraint defined a record cannot be removed as there is a reference to a record in an another table. 'A programmer ist just a tool which converts caffeine into code'

[ppp001]

Thanks. So what will happen in the database if the foreign key relation are violate in MySQL, will the database return an exception or something else ?

[seee sharp]

In that case database suppose to give constraint error. - ashish