Primary key will not allow the null values. If you want to allow null values you have to go for foriegn key.
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Try and fail but don't fail and try
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)
you are saying,ur created table with primary key allows null values na
please send ur crated table script
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.
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
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