I am creating my employee table in Oracle and for emp_date I would like to make it so the date of birth is not way back in the past and can not be set in the future?
Is this too complex to implement in the CREATE TABLE statement? if so then I guess I have to skip it because that is the part where I have to create the constraints.
, emp_dob DATE NOT NULL
CREATE TABLE employee(emp_id NUMBER(4) PRIMARY KEY
, emp_name VARCHAR2(40) NOT NULL
, emp_address VARCHAR2(60) NOT NULL
, emp_tel NUMBER(11) NOT NULL
, CONSTRAINT emp_tel_length CHECK (LENGTH(emp_tel) BETWEEN 9 and 11)
, emp_dob DATE NOT NULL
, CONSTRAINT check_date_of_birth CHECK (emp_dob BETWEEN DATE '1950-01-01' AND sysdate))
Check constraints must be deterministic. That is, a particular row must always satisfy the constraint or it must always fail to satisfy the constraint. But SYSDATE
is inherently non-deterministic since the returned value is constantly changing. Thus, you cannot define a CHECK
constraint that calls SYSDATE
or any other user-defined function.
If you try to reference SYSDATE
in the constraint definition, you'll get an error
SQL> ed
Wrote file afiedt.buf
1 create table t(
2 birth_date date check( birth_date between date '1900-01-01' and
3 sysdate )
4* )
SQL> /
sysdate )
*
ERROR at line 3:
ORA-02436: date or system variable wrongly specified in CHECK constraint
You could create a CHECK
constraint where both the minimum and maximum date were hard-coded but that would not be particularly practical since you'd have to constantly drop and recreate the constraint.
SQL> ed
Wrote file afiedt.buf
1 create table t(
2 birth_date date check( birth_date between date '1900-01-01' and
3 date '2011-12-08' )
4* )
SQL> /
Table created.
The practical way to enforce this sort of requirement would be to create a trigger on the table
CREATE OR REPLACE TRIGGER check_birth_date
BEFORE INSERT OR UPDATE ON employee
FOR EACH ROW
BEGIN
IF( :new.emp_dob < date '1900-01-01' or
:new.emp_dob > sysdate )
THEN
RAISE_APPLICATION_ERROR(
-20001,
'EMployee date of birth must be later than Jan 1, 1900 and earlier than today' );
END IF;
END;
Another way would be to create a domain birthdate, with the constraint built into the domain. This will allow you to reuse the same type in other table definitions.
CREATE DOMAIN birthdate AS date DEFAULT NULL
CHECK (value >= '1900-01-01' AND value <= now())
;
CREATE TABLE employee
( empno INTEGER NOT NULL PRIMARY KEY
, dob birthdate NOT NULL
...
);
What about another workaround
Write sysdate into a column and use it for validation. This column might be your audit column (For eg: creation date)
CREATE TABLE "AB_EMPLOYEE22"
(
"NAME" VARCHAR2 ( 20 BYTE ),
"AGE" NUMBER,
"SALARY" NUMBER,
"DOB" DATE,
"DOJ" DATE DEFAULT SYSDATE
);
Table Created
ALTER TABLE "AB_EMPLOYEE22" ADD CONSTRAINT
AGE_CHECK CHECK((ROUND((DOJ-DOB)/365)) = AGE) ENABLE;
Table Altered
You need to create a table with DATE_OF_BIRTH and the PRESENT_DATE ie I am used DATE_JOINING and then use an AGE default value by subtracting the DATE_JOINING minus DATE_OF_BIRTH.
Finally set CHECK constraint to AGE is it greater than your requirement ie I am set 20.
See below
CREATE TABLE EMPLOYEE(
NAME VARCHAR(20) NOT NULL,
DOB DATE NOT NULL,
DATE_JOINING DATE DEFAULT NOW(),
AGE INTEGER DEFAULT TIMESTAMPDIFF(YEAR,DOB,DATE_JOINING) CHECK(AGE>20)
);
INSERT INTO EMPLOYEE(NAME,DOB) VALUES('NAYAK','1998-2-3');
Query OK, 1 row affected, 1 warning (0.128 sec)
SELECT * FROM EMPLOYEE;
+-------+------------+--------------+------+
| NAME | DOB | DATE_JOINING | AGE |
+-------+------------+--------------+------+
| NAYAK | 1998-02-03 | 2019-10-15 | 21 |
+-------+------------+--------------+------+
1 row in set (0.001 sec)
INSERT INTO EMPLOYEE(NAME,DOB) VALUES('NIRAJAN','2005-2-3');
ERROR 4025 (23000): CONSTRAINT `EMPLOYEE.AGE` failed for `NAYAK`.`EMPLOYEE`
You can use interval directly:
ALTER TABLE "students"
ADD CONSTRAINT "students_must_be_over_18" CHECK (
CURRENT_TIMESTAMP - "date_of_birth" > INTERVAL '18 years'
);
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