check, not null,unique
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Answer / prasanthi
Check Constraint:
The CHECK constraint is used to limit the value range that
can be placed in a column.
not null constraint:
if we give not null constraint to any column it will not
accept null values.
Unique Conatraint:
Unique key is similar to primary key but it accepts one
null value.
For o column Setting Unique key+Not NULL we can make
Primary Key.
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