What is the difference between primary and unique key
Answers were Sorted based on User's Feedback
Answer / venkat rao
Unique key takes null value but primary key doesnot take
null value
primary key have properties of both null key and unique key
constraints
| Is This Answer Correct ? | 21 Yes | 4 No |
Answer / sudhanshu_kmr
.....primary key.......... unique key
at most one column .....:... any number of column
only unique values........... only unique values
don't accept null........... accept null
| Is This Answer Correct ? | 3 Yes | 2 No |
Answer / ashish asthana
Primay key restrict the duplicacy in the records and does
not accept null value or there are only one primary key in
a table
Unique constraint also restict the duplicacy but it accept
the null value one or more then one. We can apply unique
constraint more than one column
| Is This Answer Correct ? | 2 Yes | 2 No |
Answer / durai
primary key is does not allow duplicate which is contain not
null it is only once we can use in table
unique key allow null value
| Is This Answer Correct ? | 0 Yes | 0 No |
Answer / pradeep rajpoot
primary key no null value allow.
but unique key one null value is allow
| Is This Answer Correct ? | 0 Yes | 4 No |
ru compare the 2 null values?
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