CHECK Keyword
The CHECK keyword or constraint is used to limit the value that can be inserted in a column.
SQL CHECK ON CREATE TABLE
CREATE TABLE <TABLE_NAME> (
<COLUMN_NAME> DATATYPE CHECK (<CONDITION>)
);
Example
CREATE TABLE Employee (
EMP_AGE Integer CHECK (EMP_AGE >= 18)
);
SQL CHECK ON ALTER TABLE
ALTER TABLE <TABLE_NAME>
ADD CHECK (<CONDITION>);
Example
ALTER TABLE Employee ADD CHECK (Emp_Age >= 18);
Summary
The CHECK keyword or constraint is used to limit the value that can be inserted in a column.