The SELECT
list between the SELECT
and FROM
keywords specifies expressions that form the output rows of the SELECT
statement.
The expressions can refer to columns computed in the FROM
clause. You can specify another name for an output column by using the AS output_name
clause. This name is used to label the column to be displayed. It can also be used
to refer to the column value in the ORDER BY
and GROUP BY
clauses instead of the WHERE
or HAVING
clause. In this case, you must write out the expression.
You can enter an asterisk (*) instead of an expression in the output list to indicate all columns of the selected rows.
Examples
The SELECT
list in the following example specifies that the result set includes the empno column,
the ename column, the mgr column, and the hiredate column.
SELECT empno, ename, mgr, hiredate FROM emp;
empno | ename | mgr | hiredate
-------+--------+------+--------------------
7934 | MILLER | 7782 | 23-JAN-82 00:00:00
7782 | CLARK | 7839 | 09-JUN-81 00:00:00
7839 | KING | | 17-NOV-81 00:00:00
7788 | SCOTT | 7566 | 19-APR-87 00:00:00
7566 | JONES | 7839 | 02-APR-81 00:00:00
7369 | SMITH | 7902 | 17-DEC-80 00:00:00
7876 | ADAMS | 7788 | 23-MAY-87 00:00:00
7902 | FORD | 7566 | 03-DEC-81 00:00:00
7521 | WARD | 7698 | 22-FEB-81 00:00:00
7844 | TURNER | 7698 | 08-SEP-81 00:00:00
7499 | ALLEN | 7698 | 20-FEB-81 00:00:00
7698 | BLAKE | 7839 | 01-MAY-81 00:00:00
7654 | MARTIN | 7698 | 28-SEP-81 00:00:00
7900 | JAMES | 7698 | 03-DEC-81 00:00:00
(14 rows)