我這里創(chuàng)建了一個 goods 表，先看下里面的數(shù)據(jù)：

mysql> select * from goods;

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

| id | s_id | b_id | goods_name | goods_price | goods_desc |

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

| 1 | 1 | 5 | book | 22.35 | book |

| 2 | 2 | 5 | ball | 32.25 | ball |

| 3 | 3 | 5 | NULL | 3.23 | NULL |

| 4 | 3 | 5 | macbook | 3.23 | book |

| 5 | 3 | 5 | listbook | 2.30 | book |

| 6 | 1 | 1 | nicebook | 9999.00 | nicebook |

| 7 | 2 | 3 | googlebook | 25.30 | book |

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

1、根據(jù)s_id分組

mysql> select *,group_concat(goods_name) goods_names,group_concat(goods_desc) goods_descs,group_concat(id) ids,group_concat(goods_price) goods_prices from goods group by s_id;

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

| id | s_id | b_id | goods_name | goods_price | goods_desc | goods_names | goods_descs | ids | goods_prices |

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

| 1 | 1 | 5 | book | 22.35 | book | book,nicebook | book,nicebook | 1,6 | 22.35,9999.00 |

| 2 | 2 | 5 | ball | 32.25 | ball | ball,googlebook | ball,book | 2,7 | 32.25,25.30 |

| 3 | 3 | 5 | NULL | 3.23 | NULL | macbook,listbook | book,book | 3,4,5 | 3.23,3.23,2.30 |

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

這里使用了 group_concat()函數(shù)，主要目的是為了顯示分組的詳細(xì)信息

上面的根據(jù)單個字段分組很簡單，把相同s_id的記錄都?xì)w組了

2、根據(jù)s_id,goods_desc字段分組

分析：這里查詢分組時，會先根據(jù)s_id分組，然后對每個組里面的數(shù)據(jù)再根據(jù)goods_desc進(jìn)行分組

mysql> select *,group_concat(goods_name) goods_names,group_concat(goods_desc) goods_descs,group_concat(id) ids,group_concat(goods_price) goods_prices from goods group by s_id,goods_desc;

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

| id | s_id | b_id | goods_name | goods_price | goods_desc | goods_names | goods_descs | ids | goods_prices |

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

| 1 | 1 | 5 | book | 22.35 | book | book | book | 1 | 22.35 |

| 6 | 1 | 1 | nicebook | 9999.00 | nicebook | nicebook | nicebook | 6 | 9999.00 |

| 2 | 2 | 5 | ball | 32.25 | ball | ball | ball | 2 | 32.25 |

| 7 | 2 | 3 | googlebook | 25.30 | book | googlebook | book | 7 | 25.30 |

| 3 | 3 | 5 | NULL | 3.23 | NULL | NULL | NULL | 3 | 3.23 |

| 4 | 3 | 5 | macbook | 3.23 | book | macbook,listbook | book,book | 4,5 | 3.23,2.30 |

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

這里的goods_descs 和 上面的一比較就明白了

接下來還可以再根據(jù) goods_price 分組

mysql> select *,group_concat(goods_name) goods_names,group_concat(goods_desc) goods_descs,group_concat(id) ids,group_concat(goods_price) goods_prices from goods group by s_id,goods_desc,goods_price;

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

| id | s_id | b_id | goods_name | goods_price | goods_desc | goods_names | goods_descs | ids | goods_prices |

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

| 1 | 1 | 5 | book | 22.35 | book | book | book | 1 | 22.35 |

| 6 | 1 | 1 | nicebook | 9999.00 | nicebook | nicebook | nicebook | 6 | 9999.00 |

| 2 | 2 | 5 | ball | 32.25 | ball | ball | ball | 2 | 32.25 |

| 7 | 2 | 3 | googlebook | 25.30 | book | googlebook | book | 7 | 25.30 |

| 3 | 3 | 5 | NULL | 3.23 | NULL | NULL | NULL | 3 | 3.23 |

| 5 | 3 | 5 | listbook | 2.30 | book | listbook | book | 5 | 2.30 |

| 4 | 3 | 5 | macbook | 3.23 | book | macbook | book | 4 | 3.23 |

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

這里主要是進(jìn)行多個字段分組的時候，只需掌握分組順序后面的字段是根據(jù)前面字段分組后的內(nèi)容再進(jìn)行的分組即可。

在平時的開發(fā)任務(wù)中我們經(jīng)常會用到MYSQL的GROUP BY分組， 用來獲取數(shù)據(jù)表中以分組字段為依據(jù)的統(tǒng)計(jì)數(shù)據(jù)。比如有一個學(xué)生選課表，表結(jié)構(gòu)如下：

Table: Subject_Selection

Subject Semester Attendee

---------------------------------

ITB001 1 John

ITB001 1 Bob

ITB001 1 Mickey

ITB001 2 Jenny

ITB001 2 James

MKB114 1 John

MKB114 1 Erica

我們想統(tǒng)計(jì)每門課程有多少個學(xué)生報(bào)名，應(yīng)用如下SQL：

SELECT Subject, Count(*)

FROM Subject_Selection

GROUP BY Subject

得到如下結(jié)果：

Subject??? Count

------------------------------

ITB001???? 5

MKB114???? 2

因?yàn)楸砝镉涗浟擞?個學(xué)生選擇ITB001，2個學(xué)生選擇了MKB114。

產(chǎn)生這個結(jié)果的原因是：

GROUP BY X意思是將所有具有相同X字段值的記錄放到一個分組里。

那么GROUP BY X, Y呢？

GROUP BY X, Y意思是將所有具有相同X字段值和Y字段值的記錄放到一個分組里。

總結(jié)

以上就是這篇文章的全部內(nèi)容了，希望本文的內(nèi)容對大家的學(xué)習(xí)或者工作具有一定的參考學(xué)習(xí)價值，謝謝大家對腳本之家的支持。如果你想了解更多相關(guān)內(nèi)容請查看下面相關(guān)鏈接

總結(jié)

以上是生活随笔為你收集整理的mysql grou平by_MySQL group by对单字分组序和多字段分组的方法讲解的全部內(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。