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通过sql语句统计特定字段出现次数并排序
2022-07-05 07:38:00 【qq_29566629】
select log_ip, count(*) as number from tp_admin_log group by log_ip order by number desc
实现的功能是统计tp_admin_log表里log_ip字段各个值出现的次数并按降序排序。
ps:
要注意的是,group by函数一般要和聚合函数,比如count()函数一起使用
常用的聚合函数有:COUNT(),SUM(),AVG(),MIN(),MAX()。
COUNT(),其作用主要是返回每个组的行数,也会返回有NULL值的列,可用于数字和字符列。
SUM(),主要用于返回表达式中所有的总和,忽略NULL值,仅用于数字列。
AVG(),返回表达式所有的平均值,仅用于数字列并且自动忽略NULL值。
MIN(),返回表达式中的最小值,忽略NULL值,可用于数字、字符和日期时间列。
MAX(),返回表达式中的最大值,忽略NULL值,可用于数字、字符和日期时间列。
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