數(shù)據(jù)庫基本腳本

CREATE TABLE `a` (

`ID` INT(10) NULL DEFAULT NULL,

`class` INT(10) NULL DEFAULT NULL,

`score` INT(10) NULL DEFAULT NULL

)

COLLATE='utf8_general_ci'

ENGINE=InnoDB;

insert into a values (1,1,110);

insert into a values (2,1,120);

insert into a values (3,1,130);

insert into a values (4,1,140);

insert into a values (5,2,210);

insert into a values (6,2,220);

insert into a values (7,2,230);

insert into a values (8,2,240);

insert into a values (9,3,310);

insert into a values (10,3,320);

insert into a values (11,4,410);

1.　對 class進(jìn)行分組 取每組的前2條

select id,class,score,rank from (

select b.id,b.class,b.score,@rownum:=@rownum+1 ,

if(@pdept=b.class,@rank:=@rank+1,@rank:=1) as rank,

@pdept:=b.class

from (

select id,class,score from a order by id

) b ,(select @rownum :=0 , @pdept := null ,@rank:=0) c ) result

having rank <3 ;

rank <3 指的相當(dāng)月ruwnum<3 每組都自動(dòng)給上了序號(hào).多少條記錄就多少個(gè)序號(hào).指的是每組的.

2. ?對 class 進(jìn)行分組 ? 取記錄滿足兩天的,也就是rownum=2 的數(shù)據(jù)

select id,class,score,rank from (

select b.id,b.class,b.score,@rownum:=@rownum+1 ,

if(@pdept=b.class,@rank:=@rank+1,@rank:=1) as rank,

@pdept:=b.class

from (

select id,class,score from a order by score desc

) b ,(select @rownum :=0 , @pdept := null ,@rank:=0) c ) result

having rank =2 ;

總結(jié)

以上是生活随笔為你收集整理的mysql 排序num_MySQL 实现row_number() 分组排序功能的全部內(nèi)容，希望文章能夠幫你解決所遇到的問題。

如果覺得生活随笔網(wǎng)站內(nèi)容還不錯(cuò)，歡迎將生活随笔推薦給好友。