Figure: Table with NOT NULL
Integrity Constraints
Table EMPLOYEES
Columns: ID, LNAME, JOB, MGR, HIREDATE, SAL, COMM, DEPTNO
row 1: 100, King, AD_PRES, , 17-JUN-87, 24000, , 90
row 2: 101, Kochhar, AD_VP, 100, 21-SEP-89, 17000, , 90
row 3: 102, De Hann, AD_VP, 100, 13-JAN-93, 17000, , 90
row 4: 103, Hunold, IT_PROG, 102, 03-JAN-90, 9000, , 60
The JOB
column is annotated with the text "NOT NULL
Constraint (no row may contain a null value for this column)".
The COMM
column is annotated with the text "Absence of NOT NULL
Constraint (any row can contain a null for this column)".
The constraint on LNAME
is specified by:
ALTER TABLE "emp" MODIFY "ENAME" NOT NULL.