HAVING子句通常在GROUP BY子句后面使用,用于过滤聚合函数的结果。 如果要对查询结果进行去重操作,可以使用HAVING子句结合聚合函数来实现。例如,假设有一个表格包含学生姓名和年龄,现在想要查询不重复的学生姓名,可以使用以下SQL语句: SELECT name FROM students GROUP BY name HAVING COUNT(*) = 1; 复制代码 在上面的...
select count(1) from emp where id<100 group by sex having count(1)>4 having 其实和where一样都是过虑的作用,只是顺序不同,在有分组的时候(group by )where 是先过虑再分组计算 having是先分组计算再过虑.
1、查找表中多余的重复记录,重复记录是根据单个字段(Id)来判断 select * from 表 where Id in (select Id from 表 group byId having count(Id) > 1) 2、删除表中多余的重复记录,重复记录是根据单个字段(Id)来判断,只留有rowid最小的记录 DELETE from 表 WHERE (id) IN ( SELECT id FROM 表 GROUP B...
1.查找重复记录的几种方法: (1).SQL>select * from cz group by c1,c10,c20 having count(*) >1; 1SQL>select*fromczgroupbyc1,c10,c20havingcount(*)>1;23C1 C10 C204---512dsf623che734dff (2).SQL>select distinct * from cz; 1SQL>selectdistinct*fromcz;23C1 C10 C204---512dsf623che7...
假设你要查的表是mytable,字段是field1:select field1 from mytable group by field1 having count(0) > 1 如果要看所有的字段:select * from mytable where field1 in (select field1 from mytable group by field1 having count(0) > 1 )...
having 用来从分组的结果中筛选行 order by用来对筛选的结果进行排序 复杂查询 (1)分组函数:max min avg sum count max表示该列的最大值,min表示该列的最小值,avg表示该列的平均值,sum表示该列的和,count表示该列的行数。 注:分组函数(max、min、avg、count、sum)只能出现在选择列表中having子句、order by...
那该肿么办呢,解决办法如下: SELECT * FROM ( SELECT PROJECT_LISTING.VARIETY_NAME FROM PROJECT_LISTING WHERE PROJECT_LISTING.VARIETY_NAME IS NOT NULL GROUP BY PROJECT_LISTING.VARIETY_NAME HAVING COUNT (*) = 1 ) WHERE ROWNUM <= 5 这样就可以了。
--1,查询hm有重复的记录select hm,count(*) from a group by hm having count(*)>1--2,查询hm和xm都有重复select hm,xm count(*) from a group by hm,xm having count(*)>1
oracle查询指定字段 重复记录大于一条的记录,并统计该记录出现的总次数 --查询指定字段 重复记录大于一条的记录,并统计该记录出现的总次数 select b.ent_name,count(ent_name) from z_huhehaote_ent_item b group by b.ent_name having count(b.ent_name) > 1...
那该肿么办呢,解决办法如下: SELECT * FROM ( SELECT PROJECT_LISTING.VARIETY_NAME FROM PROJECT_LISTING WHERE PROJECT_LISTING.VARIETY_NAME IS NOT NULL GROUP BY PROJECT_LISTING.VARIETY_NAME HAVING COUNT (*) = 1 ) WHERE ROWNUM <= 5 这样就可以了。