Рассмотрим таблицу CUSTOMERS, имеющую следующие записи:
SQL> SELECT * FROM CUSTOMERS;
+----+----------+-----+-----------+----------+
| ID | NAME | AGE | ADDRESS | SALARY |
+----+----------+-----+-----------+----------+
| 1 | Maxim | 35 | Moscow | 21000.00 |
| 2 | AndreyEx | 38 | Krasnodar | 55500.00 |
| 3 | Oleg | 33 | Rostov | 34000.00 |
| 4 | Masha | 35 | Moscow | 31500.00 |
| 5 | Ruslan | 34 | Omsk | 43000.00 |
| 6 | Dima | 32 | SP | 45000.00 |
| 7 | Roma | 34 | SP | 10000.00 |
+----+----------+-----+-----------+----------+
7 rows in set (0.00 sec)
Вот некоторые простые примеры, демонстрирующие использование операторов сравнения в SQL:
Пример 1
SQL> SELECT * FROM CUSTOMERS WHERE SALARY > 45000;
Вывод
+----+----------+-----+-----------+----------+
| ID | NAME | AGE | ADDRESS | SALARY |
+----+----------+-----+-----------+----------+
| 2 | AndreyEx | 38 | Krasnodar | 55500.00 |
+----+----------+-----+-----------+----------+
1 rows in set (0.00 sec)
Пример 2
SQL> SELECT * FROM CUSTOMERS WHERE SALARY = 55000;
Вывод
+----+----------+-----+-----------+----------+
| ID | NAME | AGE | ADDRESS | SALARY |
+----+----------+-----+-----------+----------+
| 2 | AndreyEx | 38 | Krasnodar | 55500.00 |
+----+----------+-----+-----------+----------+
1 rows in set (0.00 sec)
Пример 3
SQL> SELECT * FROM CUSTOMERS WHERE SALARY != 55000;
Вывод
+----+----------+-----+-----------+----------+
| ID | NAME | AGE | ADDRESS | SALARY |
+----+----------+-----+-----------+----------+
| 1 | Maxim | 35 | Moscow | 21000.00 |
| 3 | Oleg | 33 | Rostov | 34000.00 |
| 4 | Masha | 35 | Moscow | 31500.00 |
| 5 | Ruslan | 34 | Omsk | 43000.00 |
| 6 | Dima | 32 | SP | 45000.00 |
| 7 | Roma | 34 | SP | 10000.00 |
+----+----------+-----+-----------+----------+
6 rows in set (0.00 sec)
Пример 4
SQL> SELECT * FROM CUSTOMERS WHERE SALARY <> 55000;
Вывод
+----+----------+-----+-----------+----------+
| ID | NAME | AGE | ADDRESS | SALARY |
+----+----------+-----+-----------+----------+
| 1 | Maxim | 35 | Moscow | 21000.00 |
| 3 | Oleg | 33 | Rostov | 34000.00 |
| 4 | Masha | 35 | Moscow | 31500.00 |
| 5 | Ruslan | 34 | Omsk | 43000.00 |
| 6 | Dima | 32 | SP | 45000.00 |
| 7 | Roma | 34 | SP | 10000.00 |
+----+----------+-----+-----------+----------+
6 rows in set (0.00 sec)
Пример 5
SQL> SELECT * FROM CUSTOMERS WHERE SALARY >= 4500;
Вывод
+----+----------+-----+-----------+----------+
| ID | NAME | AGE | ADDRESS | SALARY |
+----+----------+-----+-----------+----------+
| 2 | AndreyEx | 38 | Krasnodar | 55500.00 |
| 6 | Dima | 32 | SP | 45000.00 |
+----+----------+-----+-----------+----------+
2 rows in set (0.00 sec)
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