PostgreSQL - 逻辑运算符
考虑表COMPANY的记录如下 −
testdb# select * from COMPANY; id | name | age | address | salary ----+-------+-----+-----------+-------- 1 | Paul | 32 | California| 20000 2 | Allen | 25 | Texas | 15000 3 | Teddy | 23 | Norway | 20000 4 | Mark | 25 | Rich-Mond | 65000 5 | David | 27 | Texas | 85000 6 | Kim | 22 | South-Hall| 45000 7 | James | 24 | Houston | 10000 (7 rows)
以下是显示 PostgreSQL 逻辑运算符用法的简单示例。 以下 SELECT 语句列出了 AGE 大于或等于 25 且薪水大于或等于 65000.00 的所有记录。
testdb=# SELECT * FROM COMPANY WHERE AGE >= 25 AND SALARY >= 6500;
上面给出的 PostgreSQL 语句将产生以下结果 −
id | name | age | address | salary ----+-------+-----+-----------------------------------------------+-------- 1 | Paul | 32 | California | 20000 2 | Allen | 25 | Texas | 15000 4 | Mark | 25 | Rich-Mond | 65000 5 | David | 27 | Texas | 85000 (4 rows)
以下 SELECT 语句列出了 AGE 大于或等于 25 OR 工资大于或等于 65000.00 的所有记录 −
testdb=# SELECT * FROM COMPANY WHERE AGE >= 25 OR SALARY >= 6500;
上面给出的 PostgreSQL 语句将产生以下结果 −
id | name | age | address | salary ----+-------+-----+-------------+-------- 1 | Paul | 32 | California | 20000 2 | Allen | 25 | Texas | 15000 3 | Teddy | 23 | Norway | 20000 4 | Mark | 25 | Rich-Mond | 65000 5 | David | 27 | Texas | 85000 6 | Kim | 22 | South-Hall | 45000 7 | James | 24 | Houston | 10000 8 | Paul | 24 | Houston | 20000 9 | James | 44 | Norway | 5000 10 | James | 45 | Texas | 5000 (10 rows)
以下 SELECT 语句列出了 AGE 不为 NULL 的所有记录，这意味着所有记录，因为没有一条记录的 AGE 等于 NULL −
testdb=# SELECT * FROM COMPANY WHERE SALARY IS NOT NULL;
上面给出的 PostgreSQL 语句将产生以下结果 −
id | name | age | address | salary ----+-------+-----+-------------+-------- 1 | Paul | 32 | California | 20000 2 | Allen | 25 | Texas | 15000 3 | Teddy | 23 | Norway | 20000 4 | Mark | 25 | Rich-Mond | 65000 5 | David | 27 | Texas | 85000 6 | Kim | 22 | South-Hall | 45000 7 | James | 24 | Houston | 10000 8 | Paul | 24 | Houston | 20000 9 | James | 44 | Norway | 5000 10 | James | 45 | Texas | 5000 (10 rows)
