前言

MySQL8.0之前，做數(shù)據(jù)排名統(tǒng)計等相當(dāng)痛苦，因為沒有像Oracle、SQL SERVER 、PostgreSQL等其他數(shù)據(jù)庫那樣的窗口函數(shù)。但隨著MySQL8.0中新增了窗口函數(shù)之后，針對這類統(tǒng)計就再也不是事了，本文就以常用的排序?qū)嵗榻BMySQL的窗口函數(shù)。

1、準(zhǔn)備工作

創(chuàng)建表及測試數(shù)據(jù)

mysql> use testdb;

Database changed

/* 創(chuàng)建表 */

mysql> create table tb_score(id int primary key auto_increment,stu_no varchar(10),course varchar(50),score decimal(4,1)，key idx_stuNo_course(stu_no,course));

Query OK, 0 rows affected (0.03 sec)

mysql> show tables;

+------------------+

| Tables_in_testdb |

+------------------+

| tb_score |

+------------------+

/* 新增一批測試數(shù)據(jù) */

mysql> insert into tb_score(stu_no,course,score)values('2020001','mysql',90),('2020001','C++',85),('2020003','English',100),('2020002','mysql',50),('2020002','C++',70),('2020002','English',99);

Query OK, 6 rows affected (0.00 sec)

Records: 6 Duplicates: 0 Warnings: 0

mysql> insert into tb_score(stu_no,course,score)values('2020003','mysql',78),('2020003','C++',81),('2020003','English',80),('2020004','mysql',80),('2020004','C++',60),('2020004','English',100);

Query OK, 6 rows affected (0.01 sec)

Records: 6 Duplicates: 0 Warnings: 0

mysql> insert into tb_score(stu_no,course,score)values('2020005','mysql',98),('2020005','C++',96),('2020005','English',70),('2020006','mysql',60),('2020006','C++',90),('2020006','English',70);

Query OK, 6 rows affected (0.01 sec)

Records: 6 Duplicates: 0 Warnings: 0

mysql> insert into tb_score(stu_no,course,score)values('2020007','mysql',50),('2020007','C++',66),('2020007','English',76),('2020008','mysql',90),('2020008','C++',69),('2020008','English',86);

Query OK, 6 rows affected (0.01 sec)

Records: 6 Duplicates: 0 Warnings: 0

mysql> insert into tb_score(stu_no,course,score)values('2020009','mysql',70),('2020009','C++',66),('2020009','English',86),('2020010','mysql',75),('2020010','C++',76),('2020010','English',81);

Query OK, 6 rows affected (0.01 sec)

Records: 6 Duplicates: 0 Warnings: 0

mysql> insert into tb_score(stu_no,course,score)values('2020011','mysql',90),('2020012','C++',85),('2020011','English',84),('2020012','English',75),('2020013','C++',96),('2020013','English',88);

Query OK, 6 rows affected (0.01 sec)

Records: 6 Duplicates: 0 Warnings: 0

2、統(tǒng)計每門課程分?jǐn)?shù)的排名

根據(jù)每門課程的分?jǐn)?shù)從高到低進(jìn)行排名，此時，會出現(xiàn)分?jǐn)?shù)相同時怎么處理的問題，下面就根據(jù)不同的窗口函數(shù)來處理不同場景的需求

ROW_NUMBER

由結(jié)果可以看出，分?jǐn)?shù)相同時按照學(xué)號順序進(jìn)行排名

mysql> select stu_no,course,score, row_number()over(partition by course order by score desc ) rn

-> from tb_score;

+---------+---------+-------+----+

| stu_no | course | score | rn |

+---------+---------+-------+----+

| 2020005 | C++ | 96.0 | 1 |

| 2020013 | C++ | 96.0 | 2 |

| 2020006 | C++ | 90.0 | 3 |

| 2020001 | C++ | 85.0 | 4 |

| 2020012 | C++ | 85.0 | 5 |

| 2020003 | C++ | 81.0 | 6 |

| 2020010 | C++ | 76.0 | 7 |

| 2020002 | C++ | 70.0 | 8 |

| 2020008 | C++ | 69.0 | 9 |

| 2020007 | C++ | 66.0 | 10 |

| 2020009 | C++ | 66.0 | 11 |

| 2020004 | C++ | 60.0 | 12 |

| 2020003 | English | 100.0 | 1 |

| 2020004 | English | 100.0 | 2 |

| 2020002 | English | 99.0 | 3 |

| 2020013 | English | 88.0 | 4 |

| 2020008 | English | 86.0 | 5 |

| 2020009 | English | 86.0 | 6 |

| 2020011 | English | 84.0 | 7 |

| 2020010 | English | 81.0 | 8 |

| 2020003 | English | 80.0 | 9 |

| 2020007 | English | 76.0 | 10 |

| 2020012 | English | 75.0 | 11 |

| 2020005 | English | 70.0 | 12 |

| 2020006 | English | 70.0 | 13 |

| 2020005 | mysql | 98.0 | 1 |

| 2020001 | mysql | 90.0 | 2 |

| 2020008 | mysql | 90.0 | 3 |

| 2020011 | mysql | 90.0 | 4 |

| 2020004 | mysql | 80.0 | 5 |

| 2020003 | mysql | 78.0 | 6 |

| 2020010 | mysql | 75.0 | 7 |

| 2020009 | mysql | 70.0 | 8 |

| 2020006 | mysql | 60.0 | 9 |

| 2020002 | mysql | 50.0 | 10 |

| 2020007 | mysql | 50.0 | 11 |

+---------+---------+-------+----+

36 rows in set (0.00 sec)mysql> select stu_no,course,score, row_number()over(partition by course order by score desc ) rn

-> from tb_score;

+---------+---------+-------+----+

| stu_no | course | score | rn |

+---------+---------+-------+----+

| 2020005 | C++ | 96.0 | 1 |

| 2020013 | C++ | 96.0 | 2 |

| 2020006 | C++ | 90.0 | 3 |

| 2020001 | C++ | 85.0 | 4 |

| 2020012 | C++ | 85.0 | 5 |

| 2020003 | C++ | 81.0 | 6 |

| 2020010 | C++ | 76.0 | 7 |

| 2020002 | C++ | 70.0 | 8 |

| 2020008 | C++ | 69.0 | 9 |

| 2020007 | C++ | 66.0 | 10 |

| 2020009 | C++ | 66.0 | 11 |

| 2020004 | C++ | 60.0 | 12 |

| 2020003 | English | 100.0 | 1 |

| 2020004 | English | 100.0 | 2 |

| 2020002 | English | 99.0 | 3 |

| 2020013 | English | 88.0 | 4 |

| 2020008 | English | 86.0 | 5 |

| 2020009 | English | 86.0 | 6 |

| 2020011 | English | 84.0 | 7 |

| 2020010 | English | 81.0 | 8 |

| 2020003 | English | 80.0 | 9 |

| 2020007 | English | 76.0 | 10 |

| 2020012 | English | 75.0 | 11 |

| 2020005 | English | 70.0 | 12 |

| 2020006 | English | 70.0 | 13 |

| 2020005 | mysql | 98.0 | 1 |

| 2020001 | mysql | 90.0 | 2 |

| 2020008 | mysql | 90.0 | 3 |

| 2020011 | mysql | 90.0 | 4 |

| 2020004 | mysql | 80.0 | 5 |

| 2020003 | mysql | 78.0 | 6 |

| 2020010 | mysql | 75.0 | 7 |

| 2020009 | mysql | 70.0 | 8 |

| 2020006 | mysql | 60.0 | 9 |

| 2020002 | mysql | 50.0 | 10 |

| 2020007 | mysql | 50.0 | 11 |

+---------+---------+-------+----+

36 rows in set (0.00 sec)

DENSE_RANK

為了讓分?jǐn)?shù)相同時排名也相同，則可以使用DENSE_RANK函數(shù)，結(jié)果如下：

mysql> select stu_no,course,score, DENSE_RANK()over(partition by course order by score desc ) rn

-> from tb_score ;

+---------+---------+-------+----+

| stu_no | course | score | rn |

+---------+---------+-------+----+

| 2020005 | C++ | 96.0 | 1 |

| 2020013 | C++ | 96.0 | 1 |

| 2020006 | C++ | 90.0 | 2 |

| 2020001 | C++ | 85.0 | 3 |

| 2020012 | C++ | 85.0 | 3 |

| 2020003 | C++ | 81.0 | 4 |

| 2020010 | C++ | 76.0 | 5 |

| 2020002 | C++ | 70.0 | 6 |

| 2020008 | C++ | 69.0 | 7 |

| 2020007 | C++ | 66.0 | 8 |

| 2020009 | C++ | 66.0 | 8 |

| 2020004 | C++ | 60.0 | 9 |

| 2020003 | English | 100.0 | 1 |

| 2020004 | English | 100.0 | 1 |

| 2020002 | English | 99.0 | 2 |

| 2020013 | English | 88.0 | 3 |

| 2020008 | English | 86.0 | 4 |

| 2020009 | English | 86.0 | 4 |

| 2020011 | English | 84.0 | 5 |

| 2020010 | English | 81.0 | 6 |

| 2020003 | English | 80.0 | 7 |

| 2020007 | English | 76.0 | 8 |

| 2020012 | English | 75.0 | 9 |

| 2020005 | English | 70.0 | 10 |

| 2020006 | English | 70.0 | 10 |

| 2020005 | mysql | 98.0 | 1 |

| 2020001 | mysql | 90.0 | 2 |

| 2020008 | mysql | 90.0 | 2 |

| 2020011 | mysql | 90.0 | 2 |

| 2020004 | mysql | 80.0 | 3 |

| 2020003 | mysql | 78.0 | 4 |

| 2020010 | mysql | 75.0 | 5 |

| 2020009 | mysql | 70.0 | 6 |

| 2020006 | mysql | 60.0 | 7 |

| 2020002 | mysql | 50.0 | 8 |

| 2020007 | mysql | 50.0 | 8 |

+---------+---------+-------+----+

36 rows in set (0.00 sec)

RANK

DENSE_RANK的結(jié)果是分?jǐn)?shù)相同時排名相同了，但是下一個名次是緊接著上一個名次的，如果2個并列的第1之后，下一個我想是第3名，則可以使用RANK函數(shù)實現(xiàn)

mysql> select stu_no,course,score, rank()over(partition by course order by score desc ) rn

-> from tb_score;

+---------+---------+-------+----+

| stu_no | course | score | rn |

+---------+---------+-------+----+

| 2020005 | C++ | 96.0 | 1 |

| 2020013 | C++ | 96.0 | 1 |

| 2020006 | C++ | 90.0 | 3 |

| 2020001 | C++ | 85.0 | 4 |

| 2020012 | C++ | 85.0 | 4 |

| 2020003 | C++ | 81.0 | 6 |

| 2020010 | C++ | 76.0 | 7 |

| 2020002 | C++ | 70.0 | 8 |

| 2020008 | C++ | 69.0 | 9 |

| 2020007 | C++ | 66.0 | 10 |

| 2020009 | C++ | 66.0 | 10 |

| 2020004 | C++ | 60.0 | 12 |

| 2020003 | English | 100.0 | 1 |

| 2020004 | English | 100.0 | 1 |

| 2020002 | English | 99.0 | 3 |

| 2020013 | English | 88.0 | 4 |

| 2020008 | English | 86.0 | 5 |

| 2020009 | English | 86.0 | 5 |

| 2020011 | English | 84.0 | 7 |

| 2020010 | English | 81.0 | 8 |

| 2020003 | English | 80.0 | 9 |

| 2020007 | English | 76.0 | 10 |

| 2020012 | English | 75.0 | 11 |

| 2020005 | English | 70.0 | 12 |

| 2020006 | English | 70.0 | 12 |

| 2020005 | mysql | 98.0 | 1 |

| 2020001 | mysql | 90.0 | 2 |

| 2020008 | mysql | 90.0 | 2 |

| 2020011 | mysql | 90.0 | 2 |

| 2020004 | mysql | 80.0 | 5 |

| 2020003 | mysql | 78.0 | 6 |

| 2020010 | mysql | 75.0 | 7 |

| 2020009 | mysql | 70.0 | 8 |

| 2020006 | mysql | 60.0 | 9 |

| 2020002 | mysql | 50.0 | 10 |

| 2020007 | mysql | 50.0 | 10 |

+---------+---------+-------+----+

36 rows in set (0.01 sec)

這樣就實現(xiàn)了各種排序需求。

NTILE

NTILE函數(shù)的作用是對每個分組排名后，再將對應(yīng)分組分成N個小組，例如

mysql> select stu_no,course,score, rank()over(partition by course order by score desc )rn,NTILE(2)over(partition by course order by score desc ) rn_group from tb_score;

+---------+---------+-------+----+----------+

| stu_no | course | score | rn | rn_group |

+---------+---------+-------+----+----------+

| 2020005 | C++ | 96.0 | 1 | 1 |

| 2020013 | C++ | 96.0 | 1 | 1 |

| 2020006 | C++ | 90.0 | 3 | 1 |

| 2020001 | C++ | 85.0 | 4 | 1 |

| 2020012 | C++ | 85.0 | 4 | 1 |

| 2020003 | C++ | 81.0 | 6 | 1 |

| 2020010 | C++ | 76.0 | 7 | 2 |

| 2020002 | C++ | 70.0 | 8 | 2 |

| 2020008 | C++ | 69.0 | 9 | 2 |

| 2020007 | C++ | 66.0 | 10 | 2 |

| 2020009 | C++ | 66.0 | 10 | 2 |

| 2020004 | C++ | 60.0 | 12 | 2 |

| 2020003 | English | 100.0 | 1 | 1 |

| 2020004 | English | 100.0 | 1 | 1 |

| 2020002 | English | 99.0 | 3 | 1 |

| 2020013 | English | 88.0 | 4 | 1 |

| 2020008 | English | 86.0 | 5 | 1 |

| 2020009 | English | 86.0 | 5 | 1 |

| 2020011 | English | 84.0 | 7 | 1 |

| 2020010 | English | 81.0 | 8 | 2 |

| 2020003 | English | 80.0 | 9 | 2 |

| 2020007 | English | 76.0 | 10 | 2 |

| 2020012 | English | 75.0 | 11 | 2 |

| 2020005 | English | 70.0 | 12 | 2 |

| 2020006 | English | 70.0 | 12 | 2 |

| 2020005 | mysql | 98.0 | 1 | 1 |

| 2020001 | mysql | 90.0 | 2 | 1 |

| 2020008 | mysql | 90.0 | 2 | 1 |

| 2020011 | mysql | 90.0 | 2 | 1 |

| 2020004 | mysql | 80.0 | 5 | 1 |

| 2020003 | mysql | 78.0 | 6 | 1 |

| 2020010 | mysql | 75.0 | 7 | 2 |

| 2020009 | mysql | 70.0 | 8 | 2 |

| 2020006 | mysql | 60.0 | 9 | 2 |

| 2020002 | mysql | 50.0 | 10 | 2 |

| 2020007 | mysql | 50.0 | 10 | 2 |

+---------+---------+-------+----+----------+

36 rows in set (0.01 sec)

3、窗口函數(shù)小結(jié)

MySQL中還有許多其他的窗口函數(shù)，本文列舉一些，大家可以自行測試

類別

函數(shù)

說明

排序

ROW_NUMBER

為表中的每一行分配一個序號，可以指定分組(也可以不指定)及排序字段

DENSE_RANK

根據(jù)排序字段為每個分組中的每一行分配一個序號。 排名值相同時，序號相同，序號中沒有間隙(1,1,2,3這種)

RANK

根據(jù)排序字段為每個分組中的每一行分配一個序號。 排名值相同時，序號相同，但序號中存在間隙(1,1,3,4這種)

NTILE

根據(jù)排序字段為每個分組中根據(jù)指定字段的排序再分成對應(yīng)的組

分布

PERCENT_RANK

計算各分組或結(jié)果集中行的百分?jǐn)?shù)等級

CUME_DIST

計算某個值在一組有序的數(shù)據(jù)中累計的分布

前后

LEAD

返回分組中當(dāng)前行之后的第N行的值。如果不存在對應(yīng)行，則返回NULL。比如N=1時，第一名對應(yīng)的值是第二名的，最后一名結(jié)果是NULL

LAG

返回分組中當(dāng)前行之前的第N行的值。如果不存在對應(yīng)行，則返回NULL。比如N=1時，第一名對應(yīng)的值是是NUL，最后一名結(jié)果是倒數(shù)第2的值

首尾中

FIRST_VALUE

返回每個分組中第一名對應(yīng)的字段(或表達(dá)式)的值，例如本文中可以是第一名的分?jǐn)?shù)、學(xué)號等任意字段的值

LAST_VALUE

返回每個分組中最后一名對應(yīng)的字段(或表達(dá)式)的值，例如本文中可以是最后一名的分?jǐn)?shù)、學(xué)號等任意字段的值

NTH_VALUE

返回每個分組中排名第N的對應(yīng)字段(或表達(dá)式)的值，但小于N的行對應(yīng)的值是NULL

MySQL中主要的窗口函數(shù)先總結(jié)這么多，建議還是得動手實踐一番。另外，MySQL5.7及之前版本的排序方式的實現(xiàn)很多人已總結(jié)，也建議實操一番。

總結(jié)

到此這篇關(guān)于MySQL8.0窗口函數(shù)入門實踐及總結(jié)的文章就介紹到這了,更多相關(guān)MySQL8.0窗口函數(shù)實踐內(nèi)容請搜索腳本之家以前的文章或繼續(xù)瀏覽下面的相關(guān)文章希望大家以后多多支持腳本之家！

創(chuàng)作挑戰(zhàn)賽新人創(chuàng)作獎勵來咯，堅持創(chuàng)作打卡瓜分現(xiàn)金大獎

總結(jié)

以上是生活随笔為你收集整理的mysql窗口函数_MySQL8.0窗口函数入门实践及总结的全部內(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，歡迎將生活随笔推薦給好友。