MySQL查询显示连续的结果
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2022-06-26 08:30:09
mysql中 对于查询结果只显示n条连续行的问题 在领扣上碰到的一个题目:求满足条件的连续3行结果的显示 X city built a new stadium, each day many people visit it and the stats are saved as these column ......
#mysql中 对于查询结果只显示n条连续行的问题#
在领扣上碰到的一个题目:求满足条件的连续3行结果的显示
x city built a new stadium, each day many people visit it and the stats are saved as these columns: id, date, people; please write a query to display the records which have 3 or more consecutive rows and the amount of people more than 100(inclusive). for example, the table stadium: +------+------------+-----------+ | id | date | people | +------+------------+-----------+ | 1 | 2017-01-01 | 10 | | 2 | 2017-01-02 | 109 | | 3 | 2017-01-03 | 150 | | 4 | 2017-01-04 | 99 | | 5 | 2017-01-05 | 145 | | 6 | 2017-01-06 | 1455 | | 7 | 2017-01-07 | 199 | | 8 | 2017-01-08 | 188 | +------+------------+-----------+ for the sample data above, the output is: +------+------------+-----------+ | id | date | people | +------+------------+-----------+ | 5 | 2017-01-05 | 145 | | 6 | 2017-01-06 | 1455 | | 7 | 2017-01-07 | 199 | | 8 | 2017-01-08 | 188 | +------+------------+-----------+
1.首先先进行结果集的查询
select id,date,people from stadium where people>=100;
2.给查询的结果集增加一个自增列
select @newid:=@newid+1 as newid,test.* from(select @newid:=0)r, test where people>100
3.自增列和id的差值 相同即连续
select @newid:=@newid+1 as newid,test.* ,@cha:=id-@newid as cha from(select @newid:=0)r, test where people>100
4.将相同的差值 放在同一张表中,并取出连续数量大于3的
select if(count(id)>=3,count_concat(id),null)e from( select @newid:=@newid+1 as newid,test.* ,@cha:=id-@newid as cha from(select @newid:=0)r, test where people>100) as d group by cha
5.将上步得到的表和主表 取得所需要的
select id,date,people from test, (select if (count(id)>3,group_concat(id),null)e from (select @newid:=@newid+1 as newid,test.* ,@cha:=id-@newid as cha from(select @newid:=0)r, test where people>100)as d group by cha ) as f where f.e is not null and find_in_set(id,f.e);
听说还可以用存储过程来完成,不过我没尝试,稍后尝试
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