On Tue, Oct 27, 2009 at 11:38 AM, Chris Mwirigi <mwirigic@gmail.com> wrote:

alter table table_name add unique (TransactionNo, Register);

it will create a compound key that gurantees that only one combination of transactionNo and Register is allowed

Chris,

how does he take care of the primary key alias???? I presume that would be the Transaction ID which has to be unique for the composite key???