IT俱乐部 MySql mysql排名的三种常见方式

mysql排名的三种常见方式

发布: 2024年 5月 27日 550阅读

三种常见的排名

row_number、dense_rank、rank在MySQL 5.7中的实现

准备数据

表结构说明

成绩表 SC(SId,CId,score)

  • SId 学⽣编号
  • CId 课程编号
  • score 分数

创建SC表

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create table SC(
    SId varchar(10),
    CId varchar(10),
    score decimal(18,1)
);

插入数据

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-- 成绩表 SC
insert into SC values('01' , '01' , 80);
insert into SC values('01' , '02' , 90);
insert into SC values('01' , '03' , 99);
insert into SC values('02' , '01' , 70);
insert into SC values('02' , '02' , 60);
insert into SC values('02' , '03' , 80);
insert into SC values('03' , '01' , 80);
insert into SC values('03' , '02' , 80);
insert into SC values('03' , '03' , 80);
insert into SC values('04' , '01' , 50);
insert into SC values('04' , '02' , 30);
insert into SC values('04' , '03' , 20);
insert into SC values('05' , '01' , 76);
insert into SC values('05' , '02' , 87);
insert into SC values('06' , '01' , 31);
insert into SC values('06' , '03' , 34);
insert into SC values('07' , '02' , 89);
insert into SC values('07' , '03' , 98);

对SC中的学生score进行整体排名

ROW_NUMBER

1 2 3 4 5 6 7 没有重复排名，依次递增

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SET @i := 0;
SET @p := 0;
SET @q := 0;
SELECT  t1.SId
        ,t1.CId
        ,t1.score
        ,@p := t1.score
        ,if(@p=@q,@i,@i := @i+1) as dense_rank
        ,@q :=@p
from (
    SELECT  SId
            ,CId
            ,score
    from SC
    order by score desc
) t1;

DENSE_RANK

1 2 3 3 3 4 5 6 7 有重复时并列排名，最终排名也是连续的

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SET @i := 0;
SET @p := 0;
SET @q := 0;
SELECT  t1.SId
        ,t1.CId
        ,t1.score
        ,@p := t1.score
        ,if(@p=@q,@i,@i := @i+1) as dense_rank
        ,@q :=@p
from (
    SELECT  SId
            ,CId
            ,score
    from SC
    order by score desc
) t1;

RANK

1 2 3 3 3 6 7 8 有重复时并列排名，最终排名不连续

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SET @i := 0;
SET @j := 0;
SET @p := 0;
SET @q := 0;
SELECT  t1.SId
        ,t1.CId
        ,t1.score
        ,@j := @j + 1
        ,@p := t1.score
        ,if(@p=@q,@i,@i := @j) as rank
        ,@q :=@p
from (
    SELECT  SId
            ,CId
            ,score
    from SC
    order by score desc
) t1;

进行分组排名

ROW_NUMBER

查询每⻔课程成绩最好的前三名 1 2 3 4 5 6 7 没有重复排名，依次递增

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SET @i := 0;
SET @p := 0;
SET @q := 0;
SELECT  tt1.SId
        ,tt2.SName
        ,tt1.CId
        ,tt1.score
        ,tt1.rn
from (
    select  t1.SId
            ,t1.CId
            ,t1.score
            ,@p := t1.CId
            ,if(@p=@q,@i := @i + 1,@i :=1) as rn
            ,@q := @p
    from (
        select  SId
                ,CId
                ,score
        from SC
        order by CId,score DESC
    ) t1
) tt1 join Student tt2 on tt1.rn

DENSE_RANK

查询每⻔课程成绩最好的前三名 1 2 3 3 3 4 5 6 7 有重复时并列排名，最终排名也是连续的

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SET @i := 0;
SET @p := 0;
SET @q := 0;
SET @j := 0;
SET @k := 0;
SELECT  tt1.SId
        ,tt2.SName
        ,tt1.CId
        ,tt1.score
        ,tt1.rn
from (
    select  t1.SId
            ,t1.CId
            ,t1.score
            ,@p := t1.CId
            ,@j := t1.score
            ,if(@p=@q,if(@j=@k,@i,@i := @i + 1),@i :=1) as rn
            ,@q := @p
            ,@k := @j
    from (
        select  SId
                ,CId
                ,score
        from SC
        order by CId,score DESC
    ) t1
) tt1 join Student tt2 on tt1.rn

RANK

查询每⻔课程成绩最好的前三名 1 2 3 3 3 6 7 8 有重复时并列排名，最终排名不连续

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SET @i := 0;
SET @p := 0;
SET @q := 0;
SET @j := 0;
SET @k := 0;
SET @m := 1;
SELECT  tt1.SId
        ,tt2.SName
        ,tt1.CId
        ,tt1.score
        ,tt1.rn
from (
    select  t1.SId
            ,t1.CId
            ,t1.score
            ,@p := t1.CId
            ,@j := t1.score
            ,if(@p=@q,@m := @m + 1,@m := 1)
            ,if(@p=@q,if(@j=@k,@i,@i := @m),@i :=1) as rn
            ,@q := @p
            ,@k := @j
    from (
        select  SId
                ,CId
                ,score
        from SC
        order by CId,score DESC
    ) t1
) tt1 join Student tt2 on tt1.rn

总结

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