Руководство по SQL. Операторы сравнения.

Предположим, что у нас есть таблица developers:


mysql> select * from developers;
+----+-------------------+------------+--------+
| id | name              | specialty  | salary |
+----+-------------------+------------+--------+
|  1 | Eugene Suleimanov | Java       |   2000 |
|  2 | Peter Romanenko   | C++        |   2500 |
|  3 | Asya Suleimanova  | Javascript |   1500 |
|  4 | Andrei Komarov    | Php        |   2000 |
+----+-------------------+------------+--------+
4 rows in set (0.00 sec)

Ниже приведены несколько примеров использования операторов сравнения для данной таблицы:


mysql> SELECT * FROM developers WHERE specialty LIKE 'java';
+----+-------------------+-----------+--------+
| id | name              | specialty | salary |
+----+-------------------+-----------+--------+
|  1 | Eugene Suleimanov | Java      |   2000 |
+----+-------------------+-----------+--------+
1 row in set (0.00 sec)


mysql> SELECT * FROM developers WHERE salary >= 2000;
+----+-------------------+-----------+--------+
| id | name              | specialty | salary |
+----+-------------------+-----------+--------+
|  1 | Eugene Suleimanov | Java      |   2000 |
|  2 | Peter Romanenko   | C++       |   2500 |
|  4 | Andrei Komarov    | Php       |   2000 |
+----+-------------------+-----------+--------+
3 rows in set (0.00 sec)


mysql> SELECT * FROM developers WHERE salary <> 2000;
+----+------------------+------------+--------+
| id | name             | specialty  | salary |
+----+------------------+------------+--------+
|  2 | Peter Romanenko  | C++        |   2500 |
|  3 | Asya Suleimanova | Javascript |   1500 |
+----+------------------+------------+--------+
2 rows in set (0.00 sec)


mysql> SELECT * FROM developers WHERE salary = 2500;
+----+-----------------+-----------+--------+
| id | name            | specialty | salary |
+----+-----------------+-----------+--------+
|  2 | Peter Romanenko | C++       |   2500 |
+----+-----------------+-----------+--------+
1 row in set (0.00 sec)

На этом мы заканчиваем обзор примеров использования операторов сравнения структурированного языка запросов SQL.