what is Constraint? How many types of constraints in SQL ?
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Answer Posted / bimaleswar patel
Constraints are used to limit the type of data that can go
into a table.
two basic types of constraints are there
1.column level
2.table level
the difference is that column level constraints are apply
only to one column where as table level constraints are
apply to whole table
Constraints are declare at the time of table creation using
CREATE TABLE command
there are 6 constraints used in oracle
1.NOT NULL
2.UNIQUE
3.PRIMARY KEY
4.CHECK
5.DEFAULT
6.REFERENCES
| Is This Answer Correct ? | 96 Yes | 24 No |
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