计算多个日期的最大值

由于您没有提到正在使用的RDBMS，因此以下查询将适用于 几乎所有 RDBMS：

SELECt  aa.User, COUNT(bb.User ) TotalCountFROM    (SELECt DISTINCT User FROM TableName) aa        LEFT JOIN        ( SELECt  a.User FROM    TableName a         INNER JOIN         (  SELECt  Date, MAX(Value) max_val  FROM    TableName  GROUP   BY Date         ) b ON  a.Date = b.Date AND      a.Value = b.max_val        ) bb ON aa.User = bb.User GROUP   BY aa.User

• SQLFiddle演示

输出

╔══════╦════════════╗║ USER ║ TOTALCOUNT ║╠══════╬════════════╣║ Bob  ║          2 ║║ John ║          2 ║║ Paul ║          0 ║╚══════╩════════════╝