In this section, we will try to explain about important database ALTER commands that are used by a data modeler by relating it with our example data.
ALTER TABLE – Add Column:
| ALTER TABLE EMPLOYEE_DTL ADD JOIN_DATE DATE; |
ALTER TABLE – Rename Column:
| ALTER TABLE EMPLOYEE_DTL RENAME column JOIN_DATE TO EMP_JOIN_DT; |
ALTER TABLE – Modify column’s Data Type:
| ALTER TABLE EMPLOYEE_DTL MODIFY EMP_JOIN_DT VARCHAR2(10); |
ALTER TABLE – Drop Column:
| ALTER TABLE EMPLOYEE_DTL DROP COLUMN EMP_JOIN_DT; |
ALTER TABLE – Add Check Constraint:
| ALTER TABLE EMPLOYEE_DTL ADD CONSTRAINT CH_SAL CHECK(SLRY_AMT BETWEEN 4000 AND 7000); |
ALTER TABLE – Add Unique Constraint:
| ALTER TABLE EMPLOYEE_DTL ADD CONSTRAINT UN_SSN UNIQUE(SSN); |
ALTER TABLE – Disable/Enable/Drop Constraint:
| ALTER TABLE EMPLOYEE_DTL DISABLE CONSTRAINT UN_SSN;
ALTER TABLE EMPLOYEE_DTL ENABLE CONSTRAINT UN_SSN; ALTER TABLE EMPLOYEE_DTL DROP CONSTRAINT UN_SSN; |
ALTER TABLE – Modify Constraint:
| ALTER TABLE EMPLOYEE_DTL MODIFY SLRY_AMT NUMBER(7,2) NULL;
ALTER TABLE EMPLOYEE_DTL MODIFY SLRY_AMT NUMBER(7,2) NOT NULL; |
Learn data modeling design Skills on OLTP and OLAP from a US University Professor with…
These SQL commands are related with Oracle's data dictionary and can be used to get…
important DDL Statements from Oracle like Commit, Rollback, Grant, Revoke etc..
In this section, we will try to explain about important database DROP commands that are…
In this section, we will try to explain about important database DML commands that are…
In this section, we will try to explain about important database ALTER commands that are…