Update or Insert

[Anon]

Is there a command to determine whether a unique id already exsists in a database.

I want the user to just push a single button and the program to determine whether an update needs to be done or it needs to be inserted as a new record.

[lawnmowerman]

You could perform a SELECT on the database first to see if the value exists. If it does, have the code perform an UPDATE, otherwise, INSERT.

There is no single function which will determine this for you. You'll need to query the database and, based on the returned results, perform your action.

-Rich

[Anon]

IMHO, there's a mySql REPLACE which works exactly the way you need it, it DELETEs an eventually existing tuple (existing UNIQUE index) and performs an INSERT afterwards. (MySQL reference manual for V3.23.30)
This should be faster than the "manual" way.
But be careful, I think this could create problems when migrating to another DBMS...