creating a foriegn key contstraint on non primary or unique key : how to use foreign key constraint on non primary key for example ihave  two tables account and transactions i want to check the acname in transactions is one of the acname in account
table account (acno,acname,bal,type)
table transactions (tid,acno,acname,bal,credit/debit,datetime)

here transactions .acname should be equal to  account.acname.... 