MySQL中的聚合函数_MySQL
Jun 01, 2016 pm 01:18 PMbitsCN.com
1、count（）返回某列的行数
2、avg（）返回某列的平均值
3、max（）返回某列的最大值
4、min（）返回某列的最小值
5、sum（）返回某列的和
6、distinct 去除重复值
avg（）忽略值为null的行
count（*）时统计所有行，count（列）时忽略为null的行
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