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WIll Primary key allow null?

I created a table through Query where I set a particular column as PrimaryKey..It does not accept duplicate values when i try to insert them..However it accepts null..Will Primary key accept null values?


Author: Sivakumar Johnson19 Aug 2008 Member Level: Silver   Points : 0

never allows null

Author: Dharmaraj Nagarajan19 Aug 2008 Member Level: Gold   Points : 2

Primary key will not allow the null values. If you want to allow null values you have to go for foriegn key.

Author: suresh kumar19 Aug 2008 Member Level: Bronze   Points : 4

hi suresh here...
if u ve created primary key for a column it will not allow null values...if u tried to click allow nulls property in enterprise manager it shows the following error(allow nulls property can not beset on a column which is the part of the primary key)

Author: Cathrin19 Aug 2008 Member Level: Gold   Points : 0

Then how did it allow null values?

Author: Reddy19 Aug 2008 Member Level: Silver   Points : 3

Primary key will not allow the null values
you are saying,ur created table with primary key allows null values na
please send ur crated table script

Author: Saurabh Hoonka19 Aug 2008 Member Level: Silver   Points : 4

Hi Cathrin ,
look, a primary key means unique and not null. it means it would not allow either null value or not unique value. on the other hand a composite (but bot primary) or foreign key will accept a null or unique value. hope this informaion will help you.

Author: Sudha19 Aug 2008 Member Level: Silver   Points : 3

The main advantage of the primary key is not allowing the null values into columns.It would be better if you provide more details like table format.So that we can give our look on that.

Author: Ultimaterengan20 Aug 2008 Member Level: Gold   Points : 2


Primary key and unique key does not allow enter duplicate data.
Primary key and unique are Entity integrity constraints.unique key can be null but primariy key cant be null.
primariy key can be refrenced to other table as FK.We can declare only one primary key in a table but a table can have multiple unique key(column assign

i hope this may help u

Author: Sriram21 Aug 2008 Member Level: Gold   Points : 1

Primary key wont allow null values and duplicate values

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