Use table alias to reference column : Alias « Query Select « Oracle PL/SQL Tutorial






SQL>
SQL>
SQL>
SQL> create table employees(
  2    empno      NUMBER(4)
  3  , ename      VARCHAR2(8)
  4  , init       VARCHAR2(5)
  5  , job        VARCHAR2(8)
  6  , mgr        NUMBER(4)
  7  , bdate      DATE
  8  , msal       NUMBER(6,2)
  9  , comm       NUMBER(6,2)
 10  , deptno     NUMBER(2) ) ;

Table created.

SQL>
SQL>
SQL> insert into employees values(1,'Jason',  'N',  'TRAINER', 2,   date '1965-12-18',  800 , NULL,  10);

1 row created.

SQL> insert into employees values(2,'Jerry',  'J',  'SALESREP',3,   date '1966-11-19',  1600, 300,   10);

1 row created.

SQL> insert into employees values(3,'Jord',   'T' , 'SALESREP',4,   date '1967-10-21',  1700, 500,   20);

1 row created.

SQL> insert into employees values(4,'Mary',   'J',  'MANAGER', 5,   date '1968-09-22',  1800, NULL,  20);

1 row created.

SQL> insert into employees values(5,'Joe',    'P',  'SALESREP',6,   date '1969-08-23',  1900, 1400,  30);

1 row created.

SQL> insert into employees values(6,'Black',  'R',  'MANAGER', 7,   date '1970-07-24',  2000, NULL,  30);

1 row created.

SQL> insert into employees values(7,'Red',    'A',  'MANAGER', 8,   date '1971-06-25',  2100, NULL,  40);

1 row created.

SQL> insert into employees values(8,'White',  'S',  'TRAINER', 9,   date '1972-05-26',  2200, NULL,  40);

1 row created.

SQL> insert into employees values(9,'Yellow', 'C',  'DIRECTOR',10,  date '1973-04-27',  2300, NULL,  20);

1 row created.

SQL> insert into employees values(10,'Pink',  'J',  'SALESREP',null,date '1974-03-28',  2400, 0,     30);

1 row created.

SQL>
SQL>
SQL>
SQL>
SQL> select e.ename, e.init, e.job
  2  from   employees e
  3  where  e.deptno = 20;

ENAME    INIT  JOB
-------- ----- --------
Jord     T     SALESREP
Mary     J     MANAGER
Yellow   C     DIRECTOR

SQL>
SQL>
SQL> drop table employees;

Table dropped.

SQL>
SQL>








2.12.Alias
2.12.1.Using Column Aliases
2.12.2.Use table alias to reference column
2.12.3.Use spaces and preserve the case of your alias text
2.12.4.Use the optional AS keyword before the alias
2.12.5.An alias is required when using TO_CHAR to 'pretty up' the output
2.12.6.Column for alias
2.12.7.Sum alias
2.12.8.SUBSTR with column alias
2.12.9.Column name alias with space
2.12.10.Column name alias for count function