Constraints are used to restrict the data inserted at a particular column. Constraints can be used in such a way that a value can only be inserted if it satisfies the condition given in constraints. We can give the below parameter during CREATE TABLE command to add a constraint.
CREATE TABLE DBSET1.TAB1 (STUDENT_ID CHAR(10) NOT NULL, ENROLLMENT_ID CHAR(20) NOT NULL, NAME VARCHAR(50), AGE SMALLINT CONSTRAINT NUMBER CHECK (AGE >=3 AND AGE <=16) PRIMARY KEY (STUDENT_ID));
The CONSTRAINT NUMBER CHECK reserved words can be followed by the permissible range that a column can have. It can be accompanied by logical operators like AND, NOT, OR to adjust the value range.