what is difference between primary key and Unique
Answers were Sorted based on User's Feedback
Answer / naresh
Primary key:it can not be null
Unique:it can have only one null value in a table.
| Is This Answer Correct ? | 13 Yes | 2 No |
Answer / thaqi
unique key: allows NULL values and doesn't allow duplicate
values.
primary key:doesn't allow both NULL and duplicate values
| Is This Answer Correct ? | 11 Yes | 1 No |
Answer / sivasankar k.c
Primary key: it is clustered index. it not allows null
values. Only one primary in each table.
Unique Key: it is non clustered index. Unique key allows
null values.its allows only one null value. More than one
unique key in table.
| Is This Answer Correct ? | 8 Yes | 2 No |
Answer / navneet sharma
Unique key allow null value and it is a non cluster index
Primary key does not allow null value and it is custer index
| Is This Answer Correct ? | 4 Yes | 0 No |
Answer / suresh kaudi
Primary Key: Not allow null values,when we make primary key
automatically create cluster index,primary key we make
other foreign key.
Unique key: allow one null value,we can't make it foreign
key to other table.here we cane make only non-cluster index
| Is This Answer Correct ? | 2 Yes | 0 No |
Answer / sunil kumar mishra
Primary key is a particular coloum that is unique in every
tuple is called primary key and ofenly it does not support
null values since it is used to uniquely identitfy row in a
table(Relation) and automatically does go to replace into
clustered index and support distinct value and Each table
should have a primary key, and each table can have only one
primary key.(Primary keys must contain unique values)
Unique value-
Unique values is same, in some manner, primary key since
You can have many UNIQUE constraints per table but primaty
key kan have one in each table.it support nonClustered
index.
| Is This Answer Correct ? | 0 Yes | 0 No |
Answer / suresh kaudi
Primary key : Not Accept null values
Unique key : Accept Onley one null value
When you Make Primary key In a table cluster index create
Automatically mean default.
Unique Key create Automatically non-cluster index
| Is This Answer Correct ? | 0 Yes | 0 No |
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