SQL GROUP BY子句用于協(xié)同SELECT語(yǔ)句用來(lái)安排相同的數(shù)據(jù)分組。
GROUP BY子句在SELECT語(yǔ)句的WHERE子句之后并ORDER BY子句之前。
GROUP BY子句的基本語(yǔ)法如下。GROUP BY子句中必須遵循WHERE子句中的條件,如果使用必須先于ORDER BY子句。
SELECT column1, column2 FROM table_name WHERE [ conditions ] GROUP BY column1, column2 ORDER BY column1, column2
考慮到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 | +----+----------+-----+-----------+----------+
如果你想知道每個(gè)客戶的薪水的總額,使用GROUP BY查詢?nèi)缦滤荆?/p>
SQL> SELECT NAME, SUM(SALARY) FROM CUSTOMERS GROUP BY NAME;
這將產(chǎn)生以下結(jié)果:
+----------+-------------+ | NAME | SUM(SALARY) | +----------+-------------+ | Chaitali | 6500.00 | | Hardik | 8500.00 | | kaushik | 2000.00 | | Khilan | 1500.00 | | Komal | 4500.00 | | Muffy | 10000.00 | | Ramesh | 2000.00 | +----------+-------------+
現(xiàn)在,讓我們有如下表,客戶表中有以下重名記錄:
+----+----------+-----+-----------+----------+ | ID | NAME | AGE | ADDRESS | SALARY | +----+----------+-----+-----------+----------+ | 1 | Ramesh | 32 | Ahmedabad | 2000.00 | | 2 | Ramesh | 25 | Delhi | 1500.00 | | 3 | kaushik | 23 | Kota | 2000.00 | | 4 | kaushik | 25 | Mumbai | 6500.00 | | 5 | Hardik | 27 | Bhopal | 8500.00 | | 6 | Komal | 22 | MP | 4500.00 | | 7 |