Primary key type question

[Anon]

Hi There,

I have a MySQL table, MYTABLE, with three columns...

id session pid

All the fields can store duplicates of the same info, except \'id\' and \'session\'. ie:

12 300 444

12 301 238
13 300 444
12 301 111

Notice that rows 2 and 4 have the same values for both \'id\' and \'session\'... I would like to make it so that this can\'t happen.

If someone could post a sql statement to help me out I would appreciate it.

Thanks,

-dr

[kparker]

If you can't recreate the table, you can always add a unique index that enforces this requirement:

   create unique index no_dups on mytable (id, session);

However, you're going to have problems with the existing duplicate data that's already in the table.

Alternative, if you can redefine the table, you might prefer to add

   primary key (id, session)

to the table definition.

[Anon]

Thank you... worked great.

-dr