eg: select distinct * from table(表名) where 条件 2.存在部分字段相同(有key, id 即唯一键)如:id列不同,id类型为int,自增字段,使用聚合函数max或其他 eg: select * from table where id in ( select max(id) from table group by [去重复字段表1,...] having COUNT(*)>1 ) 3.没有唯一键 I...
好,我们首先要解决这个问题,我试过薪资排序等一些手法,都不能摆脱MAX和GROUP BY的坑,唯一办法就是不使用MAX,我想到的办法是 可以利用 in这个语法,让筛选直接匹配对应的薪资,通过子查询,筛选出部门最高薪资,在用条件语句 in 这个薪资匹配,这样可以脱离MAX和GROUP的坑,结果发现还是错误,仔细一看,在d002部门中10006...
string2int select cast(click as int) select cast('1'as int) sql关于group by和max函数一起使用的坑(同理,求部门最高工资)
「ERROR 1055 (42000): Expression #4 of SELECT list is not in GROUP BY clause and contains nonaggregated column 'demo.g.grade_course' which is not functionally dependent on columns in GROUP BY clause; this is incompatible with sql_mode=only_full_group_by」 原因解析:由于grade_course 不在 gr...
有一个SQL查询问题。让我们以这个示例数据为例 itemIDcatIDattrib1attrib2 11105 21107 31510 421815 我想返回每个类别的最佳商品(attrib1优先于attrib2) 显然,“从test_table GROUP BY catID中选择SELECT catID,MAX(attrib1),MAX(attrib2)”不起作用,因为它将为第一只猫返回10和10。
Angular 1.4 ng-if and ng-repeat to menu Add instance of Generic List to object using reflection Issue with qtvirtualkeyboard while upgrading from Qt 5.9 to 5.12 BeautifulSoup Not Returning Twitch.tv Viewcount How do I use /deep/ or >>> or ::v-deep in Vue.js?
由此可以验证在mysql中的group by函数,默认分组后取的第一条数据为根据聚簇索引分组得来的第一条记录这一说法; 查询每科目最优成绩及学生 方案一: 采用先排序后分组 还是回到上述案例中,基于上面的sql的前提下,我们可以考虑先给考试成绩按照分数从高到低按照分数排个序,得到一张临时表; ...
In episode 3: The most essential SQL functions (MAX, MIN, SUM, COUNT, AVG), GROUP BY, and two more SQL clauses (ORDER BY, DISTINCT).
Where OrderDate In (Select Max(OrderDate) From Orders Group by Convert(char(6),OrderDate,112))--112表示YYYYMMDD char(6)提取YYYYMM 3. Select字句在逻辑上是SQL语句最后进行处理的最后一步,所以,以下查询会发生错误: SELECT OrderYear, COUNT(DISTINCT CustomerID) AS NumCusts ...
I tried grouping ProducerID/TypeID/AgentID and doing a MAX() on the effective date to narrow it down, but for whatever reason I just am not getting it to work. I'm having a hard enough time querying this in t-sql, let alone LINQ. ...