Unique and Non-unique keys

Discuss the difference between unique and non-unique keys

kh_trnh
Profile Answers by kh_trnh Questions by kh_trnh
Jul 8th, 2008
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KamalChauhan
Profile Answers by KamalChauhan

Jul 11th, 2008

Unique keys can have only one null value or rather i should say that every value in the column(which is marked as unique key) must be unique.

mudkhedkar
Profile Answers by mudkhedkar

Nov 7th, 2008

Unique - Take for example employee table, it has column empno which is called as unique key where as non-unique key is column workdept, i.e when we do relationship between two tables as employee & department tables, dept. table also contains deptno as column so it is called as non-unique key.