【AntDB数据库 SQL语法专栏】——运算符（5）

实例

创建 STUDENT表，数据内容如下：

antdb=# select * from student;
 id | name  | age | gender  | score
----+-------+-----+---------+--------
  1 | Paul  |  16 | male    |  100
  2 | Allen |  16 | famale  |  98
  3 | Teddy |  17 | famale  |  99
  4 | Mark  |  16 | male    |  78
  5 | David |  18 | male    |  89
  6 | Kim   |  17 | male    |  95
  7 | James |  17 | male    |  100
  8 | Kate  |  16 | famale  |  96
  9 | Lily  |  16 | famale  |  85
(9 rows)

读取 age 字段大于等于 17 且 score 字段大于等于 90 的数据：

antdb=# SELECT * FROM student WHERE age >= 17 AND score >= 90;
 id | name  | age | gender  | score
----+-------+-----+---------+--------
  3 | Teddy |  17 | famale  |  99
  6 | Kim   |  17 | male    |  95
  7 | James |  17 | male    |  100
(3 rows)

读取 age 字段大于等于 17 或 score 字段大于等于 90 的数据：

antdb=# SELECT * FROM student WHERE age >= 17 OR score >= 90;
 id | name  | age | gender  | score
----+-------+-----+---------+--------
  1 | Paul  |  16 | male    |  100
  2 | Allen |  16 | famale  |  98
  3 | Teddy |  17 | famale  |  99
  5 | David |  18 | male    |  89
  6 | Kim   |  17 | male    |  95
  7 | James |  17 | male    |  100
  8 | Kate  |  16 | famale  |  96
(7 rows)

读取 score 字段不为 NULL 的数据：

antdb=#  SELECT * FROM student WHERE score IS NOT NULL;
 id | name  | age | gender  | score
----+-------+-----+---------+--------
  1 | Paul  |  16 | male    |  100
  2 | Allen |  16 | famale  |  98
  3 | Teddy |  17 | famale  |  99
  4 | Mark  |  16 | male    |  78
  5 | David |  18 | male    |  89
  6 | Kim   |  17 | male    |  95
  7 | James |  17 | male    |  100
  8 | Kate  |  16 | famale  |  96
  9 | Lily  |  16 | famale  |  85
(9 rows)