SQL Having子句
HAVING子句允許您指定過濾器的條件,分組結果會出現在最終結果。
WHERE子句所選列的條件,而由GROUP BY子句條件創建分組的HAVING子句。
語法
下麵是HAVING子句在查詢中的位置:
SELECT FROM WHERE GROUP BY HAVING ORDER BY
HAVING子句必須遵循GROUP BY子句中的查詢,如果使用也必須先於ORDER BY子句。 下麵是SELECT語句,包括HAVING子句的語法:
SELECT column1, column2 FROM table1, table2 WHERE [ conditions ] GROUP BY column1, column2 HAVING [ conditions ] ORDER BY column1, column2
例子:
考慮CUSTOMERS表具有以下記錄:
+----+----------+-----+-----------+----------+ | ID | NAME | AGE | ADDRESS | SALARY | +----+----------+-----+-----------+----------+ | 1 | Ramesh | 32 | Ahmedabad | 2000.00 | | 2 | Khilan | 25 | Delhi | 1500.00 | | 3 | kaushik | 23 | Kota | 2000.00 | | 4 | Chaitali | 25 | Mumbai | 6500.00 | | 5 | Hardik | 27 | Bhopal | 8500.00 | | 6 | Komal | 22 | MP | 4500.00 | | 7 | Muffy | 24 | Indore | 10000.00 | +----+----------+-----+-----------+----------+
下麵是示例,這將顯示記錄age大於或等於2的數據量:
SQL > SELECT ID, NAME, AGE, ADDRESS, SALARY FROM CUSTOMERS GROUP BY age HAVING COUNT(age) >= 2;
這將產生以下結果:
+----+--------+-----+---------+---------+ | ID | NAME | AGE | ADDRESS | SALARY | +----+--------+-----+---------+---------+ | 2 | Khilan | 25 | Delhi | 1500.00 | +----+--------+-----+---------+---------+