MySQL column No duplicates

[Anon]

Am I right that when In table column is primary_key then I can not use identical values??
Or not then what should I do (I can't use auto increment function)

[Anon]

Yes. The primary key has to be a unique value.

[Anon]

when we insert data into database,if the identical data is present it should not be updated and show some message

example: if an employee got his ID as 145
then we enter the same ID number for another employee it should show some message as this ID already exists