SQL GROUP BY 语句

GROUP BY 语句
GROUP BY 语句用于结合合计函数，根据一个或多个列对结果集进行分组。
SQL GROUP BY 语法

SELECT COLUMN_NAME,AGGREGATE_FUNCTION(COLUMN_NAME) FROM TABLE_NAME WHERE COLUMN_NAME OPERATOR VALUE GROUP BY COLUMN_NAME

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SQL GROUP BY 实例
TROUSERS表:

SERIALNUMBER	MANUFACTURER	IMPORT_PRICE	EXPORT_PRICE
1	XTEP	110.78	224.90
2	361	151.12	224.90
3	ERKE
4		157.89	224.00
5	XTEP	120.78	204.90
6	361	231.12	624.00

查找每一种品牌的出口总和:

SELECT MANUFACTURER , SUM(EXPORT_PRICE) FROM TROUSERS GROUP BY MANUFACTURER 

MANUFACTURER	SUM(EXPORT_PRICE)
	224
ERKE
361	948
XTEP	429.8

如果不用GROUP BY 的情况:

SELECT MANUFACTURER , SUM(EXPORT_PRICE) FROM TROUSERS