PostgreSQL �� SQL99 ��boolean �����Ƥ��ޤ���boolean �ˤ� 2 �Ĥξ��֤Τ��� 1 �Ĥ��ݻ��Ǥ��ޤ����ֿ���true�ˡ� �ޤ��ϡֵ���false�ˡפǤ����� 3 �ξ��֤Ǥ��� ��������unknown�ˡפ� SQL �ˤ����� NULL ��ɽ������ޤ���
�ֿ���true�ˡ��֤��Ф���ͭ���ʥ�ƥ���ͤˤϼ��Τ�Τ�����ޤ���
| TRUE |
| 't' |
| 'true' |
| 'y' |
| 'yes' |
| '1' |
| FALSE |
| 'f' |
| 'false' |
| 'n' |
| 'no' |
| '0' |
Example 3-2. boolean ��Ȥä�
CREATE TABLE test1 (a boolean, b text); INSERT INTO test1 VALUES (TRUE, 'sic est'); INSERT INTO test1 VALUES (FALSE, 'non est'); SELECT * FROM test1; a | b ---+--------- t | sic est f | non est SELECT * FROM test1 WHERE a; a | b ---+--------- t | sic est
Example 3-2 �� t ����� f ��Ȥä� boolean ���ͤ����Ϥ��줿���Ȥ��Ƥ��ޤ���
Tip: boolean ���ͤ�¾�Υǡ�������ľ�ܥ��㥹�ȤǤ��ޤ���(�㤨�С�CAST (boolval AS integer) �ϵ�ǽ���ޤ�����ˡ�Ȥ��Ƥ� CASE ʸ�Dz��Ǥ��ޤ���CASE WHEN boolval THEN 'value if true' ELSE 'value if false' END�� Section 4.12 �⻲�Ȥ��Ƥ���������
boolean ����¸�� 1 �Х��Ȼ��Ѥ��ޤ���