SQL Not null Constraints

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SQL Not null Constraints

Not null Constraints does not allow to enter null value on a particular column in a table. You can apply not null constraints on more than one column in same table.

Advantage of not null Constraints

If you do not enter the value in any particular column in the table that column automatically take null but by using not null constraints we can forcefully enter the value into the column.

This constraints allows to enter null value.


create table employee
(eid number(3) unique,
ename varchar2(15) not null,
sal number(5));

Note: If you avoid the not null constraints property then it gives the following error messages "ora- cannot insert null".

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