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What is the diffrence between unique and primary key constraints?

19th Jan 2016, 2:10 PM
Aakash Bidlan
Aakash Bidlan - avatar
3 odpowiedzi
+ 1
the Primary Key does both, Makes values Unique and NOT NULL, it can only be used once per table, as of UNIQUE can be used multiple times in a table.
8th Mar 2016, 1:27 PM
Euly Rodriguez
Euly Rodriguez - avatar
+ 1
primary keys are use to create foreign keys and normalize The table, that means, avoid duplicate data and improve performance
30th Jun 2016, 1:37 PM
David Alexander Miranda Grinstein
David Alexander Miranda Grinstein - avatar
- 1
Unique can be null but primary key will never accept null.
30th Jan 2016, 1:44 PM
Esmatullah Arifi
Esmatullah Arifi - avatar