Creates an index on the new added column : Create Index « Index « Oracle PL/SQL Tutorial

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SQL>
SQL> CREATE TABLE employee
  2  (employee_id         NUMBER(7),
  3   last_name           VARCHAR2(25),
  4   first_name          VARCHAR2(25),
  5   userid              VARCHAR2(8),
  6   start_date          DATE,
  7   comments            VARCHAR2(255),
  8   manager_id          NUMBER(7),
  9   title               VARCHAR2(25),
 10   department_id       NUMBER(7),
 11   salary              NUMBER(11, 2),
 12   commission_pct      NUMBER(4, 2)
 13  );

Table created.

SQL>
SQL> INSERT INTO employee VALUES (1, 'V', 'Ben', 'cv',to_date('03-MAR-90 8:30', 'dd-mon-yy hh24:mi'),NULL, NULL, 'PRESIDENT', 50, 2500, NULL);

1 row created.

SQL> INSERT INTO employee VALUES (2, 'N', 'Haidy', 'ln', '08-MAR-90', NULL,1, 'VP, OPERATIONS', 41, 1450, NULL);

1 row created.

SQL> INSERT INTO employee VALUES (3, 'N', 'Molly', 'mn', '17-JUN-91',NULL, 1, 'VP, SALES', 31, 1400, NULL);

1 row created.

SQL> INSERT INTO employee VALUES (4, 'S', 'Mark', 'mq', '07-APR-90',NULL, 1, 'VP, FINANCE', 10, 1450, NULL);

1 row created.

SQL> INSERT INTO employee VALUES (5, 'R', 'AUDRY', 'ar', '04-MAR-90',NULL, 1, 'VP, ADMINISTRATION', 50, 1550, NULL);

1 row created.

SQL> INSERT INTO employee VALUES (6, 'U', 'MOLLY', 'mu', '18-JAN-91',NULL, 2, 'WAREHOUSE MANAGER', 41, 1200, NULL);

1 row created.

SQL> INSERT INTO employee VALUES (7, 'M', 'ROBERTA', 'rm', '14-MAY-90',NULL, 2, 'WAREHOUSE MANAGER', 41, 1250, NULL);

1 row created.

SQL> INSERT INTO employee VALUES (8, 'B', 'BEN', 'ry', '07-APR-90', NULL, 2,'WAREHOUSE MANAGER', 41, 1100, NULL);

1 row created.

SQL> INSERT INTO employee VALUES (9, 'C', 'Jane', 'ac', '09-FEB-92',NULL, 2, 'WAREHOUSE MANAGER', 41, 1300, NULL);

1 row created.

SQL> INSERT INTO employee VALUES (10, 'H', 'Mart', 'mh', '27-FEB-91', NULL, 2,'WAREHOUSE MANAGER', 41, 1307, NULL);

1 row created.

SQL>
SQL>
SQL> -- Adds the new column
SQL> ALTER TABLE employee ADD employee_dup_id VARCHAR2(7);

Table altered.

SQL>
SQL> -- Updates the new column with the value of the employee_id column
SQL> UPDATE employee
  2  SET    employee_dup_id = employee_id;

10 rows updated.

SQL>
SQL>
SQL> -- Creates an index on the new column
SQL> CREATE UNIQUE INDEX employee_test_idx2
  2     ON employee(employee_dup_id);

Index created.

SQL>
SQL> drop table employee;

Table dropped.

SQL>