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                ## 分組查詢 >[info] 分組查詢又叫統計查詢,因為分組查詢的目的,絕大多數是用于統計,因此大家將重點要放到聚合函數在select查詢中的使用技巧。 ### 涉及到方法 1. group方法:對應原生的 GROUP BY 子句,分組字段必須是表中存在的字段,而不能是通過select計算出來的; 2. having方法:對應原生的HAVING 子句,有點類似where方法,但是having方法中,可以使用select可計算的字段名做為查詢條件,如直接使用聚合函數(具體參看后面案例)。 * * * * * ### 讓我們開始本章的學習之旅吧~~
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