溫馨提示×

您好，登錄后才能下訂單哦！

密碼登錄×
登錄注冊(cè)×
其他方式登錄
點(diǎn)擊 登錄注冊(cè) 即表示同意《億速云用戶服務(wù)條款》

MySQL8.0窗口函數(shù)實(shí)例詳解

發(fā)布時(shí)間：2020-06-28 13:43:39 來源：億速云 閱讀：137 作者：清晨 欄目：開發(fā)技術(shù)

小編給大家分享一下MySQL8.0窗口函數(shù)實(shí)例詳解，希望大家閱讀完這篇文章后大所收獲，下面讓我們一起去探討吧！

MySQL8.0之前，做數(shù)據(jù)排名統(tǒng)計(jì)等相當(dāng)痛苦，因?yàn)闆]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(duì)這類統(tǒng)計(jì)就再也不是事了，

1、準(zhǔn)備工作

創(chuàng)建表及測(cè)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(cè)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(jì)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(shí)，會(huì)出現(xiàn)分?jǐn)?shù)相同時(shí)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(chǎng)景的需求

ROW_NUMBER

由結(jié)果可以看出，分?jǐn)?shù)相同時(shí)按照學(xué)號(hào)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(shí)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(shí)排名相同了，但是下一個(gè)名次是緊接著上一個(gè)名次的，如果2個(gè)并列的第1之后，下一個(gè)我想是第3名，則可以使用RANK函數(shù)實(shí)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(shí)現(xiàn)了各種排序需求。

NTILE

NTILE函數(shù)的作用是對(duì)每個(gè)分組排名后，再將對(duì)應(yīng)分組分成N個(gè)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(cè)試

類別函數(shù)說明
排序ROW_NUMBER為表中的每一行分配一個(gè)序號(hào)，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(gè)分組中的每一行分配一個(gè)序號(hào)。 排名值相同時(shí)，序號(hào)相同，序號(hào)中沒有間隙（1,1,2,3這種）
RANK根據(jù)排序字段為每個(gè)分組中的每一行分配一個(gè)序號(hào)。 排名值相同時(shí)，序號(hào)相同，但序號(hào)中存在間隙（1,1,3,4這種）
NTILE根據(jù)排序字段為每個(gè)分組中根據(jù)指定字段的排序再分成對(duì)應(yīng)的組
分布PERCENT_RANK計(jì)算各分組或結(jié)果集中行的百分?jǐn)?shù)等級(jí)
CUME_DIST計(jì)算某個(gè)值在一組有序的數(shù)據(jù)中累計(jì)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(duì)應(yīng)行，則返回NULL。比如N=1時(shí)，第一名對(duì)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(duì)應(yīng)行，則返回NULL。比如N=1時(shí)，第一名對(duì)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(gè)分組中第一名對(duì)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(hào)等任意字段的值
LAST_VALUE返回每個(gè)分組中最后一名對(duì)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(hào)等任意字段的值
NTH_VALUE

返回每個(gè)分組中排名第N的對(duì)應(yīng)字段（或表達(dá)式）的值，但小于N的行對(duì)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(dòng)手實(shí)踐一番。另外，MySQL5.7及之前版本的排序方式的實(shí)現(xiàn)很多人已總結(jié)，也建議實(shí)操一番。


看完了這篇文章，相信你對(duì)MySQL8.0窗口函數(shù)實(shí)例詳解有了一定的了解，想了解更多相關(guān)知識(shí)，歡迎關(guān)注億速云行業(yè)資訊頻道，感謝各位的閱讀！

向AI問一下細(xì)節(jié)

免責(zé)聲明：本站發(fā)布的內(nèi)容（圖片、視頻和文字）以原創(chuàng)、轉(zhuǎn)載和分享為主，文章觀點(diǎn)不代表本網(wǎng)站立場(chǎng)，如果涉及侵權(quán)請(qǐng)聯(lián)系站長(zhǎng)郵箱：is@yisu.com進(jìn)行舉報(bào)，并提供相關(guān)證據(jù)，一經(jīng)查實(shí)，將立刻刪除涉嫌侵權(quán)內(nèi)容。

AI
助
手