boolean，which has three states: True,False,NULL。(NULL表示未知状态，Unknown)。 Storage Size : 1 byte.
| PostgreSQL type | .NET type | NpgsqlDbType | DbType |
|---|---|---|---|
| boolean | 未加非空约束：bool? 加了非空约束：bool |
Boolean | Boolean |
字面值
INSERT INTO t_boolean(my_boolean)VALUES(TRUE);
INSERT INTO t_boolean(my_boolean)VALUES(FALSE);
INSERT INTO t_boolean(my_boolean)VALUES(true);
INSERT INTO t_boolean(my_boolean)VALUES(false);
INSERT INTO t_boolean(my_boolean)VALUES('TRUE');
INSERT INTO t_boolean(my_boolean)VALUES('FALSE');
INSERT INTO t_boolean(my_boolean)VALUES('true');
INSERT INTO t_boolean(my_boolean)VALUES('false');
INSERT INTO t_boolean(my_boolean)VALUES('yes');
INSERT INTO t_boolean(my_boolean)VALUES('no');
INSERT INTO t_boolean(my_boolean)VALUES('on');
INSERT INTO t_boolean(my_boolean)VALUES('off');
INSERT INTO t_boolean(my_boolean)VALUES('YES');
INSERT INTO t_boolean(my_boolean)VALUES('NO');
INSERT INTO t_boolean(my_boolean)VALUES('ON');
INSERT INTO t_boolean(my_boolean)VALUES('OFF');
INSERT INTO t_boolean(my_boolean)VALUES('Y');
INSERT INTO t_boolean(my_boolean)VALUES('N');
INSERT INTO t_boolean(my_boolean)VALUES('T');
INSERT INTO t_boolean(my_boolean)VALUES('F');
INSERT INTO t_boolean(my_boolean)VALUES('y');
INSERT INTO t_boolean(my_boolean)VALUES('n');
INSERT INTO t_boolean(my_boolean)VALUES('t');
INSERT INTO t_boolean(my_boolean)VALUES('f');
INSERT INTO t_boolean(my_boolean)VALUES('1');
INSERT INTO t_boolean(my_boolean)VALUES('0');
INSERT INTO t_boolean(my_boolean)VALUES(NULL);
逻辑运算符
| A | B | A AND B | A OR B | NOT A |
|---|---|---|---|---|
| True | NULL | NULL | True | False |
| False | NULL | False | NULL | True |
| NULL | NULL | NULL | NULL | NULL |
比较运算符
expression IS TRUE;
expression IS FALSE;
expression IS UNKNOWN;
select (1>2) IS UNKNOWN;