【AntDB数据库 SQL语法专栏】——运算符（3）

比较运算符

假设变量 a 为 10，变量 b 为 20，则：

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score 字段大于 95 的数据：

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

读取 score 字段等于 100 的数据：

antdb=# SELECT * FROM student WHERE score = 100;
 id | name  | age | gender  | score
----+-------+-----+---------+--------
  1 | Paul  |  16 | male    |  100
  7 | James |  17 | male    |  100
(2 rows)

读取 score 字段不等于 100 的数据：

antdb=#  SELECT * FROM student WHERE score != 100;
 id | name  | age | gender  | score
----+-------+-----+---------+--------
  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
  8 | Kate  |  16 | famale  |  96
  9 | Lily  |  16 | famale  |  85
(7 rows)

antdb=# SELECT * FROM student WHERE score <> 100;
 id | name  | age | gender  | score
----+-------+-----+---------+--------
  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
  8 | Kate  |  16 | famale  |  96
  9 | Lily  |  16 | famale  |  85
(7 rows)

读取 score 字段大于等于 90 的数据：

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