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Unique and Non-unique keys
Discuss the difference between unique and non-unique keys
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.
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.
