MySQL group by对单字分组序和多字段分组的方法解说
发布时间：2022-03-08 07:54:03 所属栏目：MySql教程 来源：互联网
导读：我这里创建了一个 goods 表，先看下里面的数据： mysql select * from goods; +----+------+------+------------+-------------+------------+ | id | s_id | b_id | goods_name | goods_price | goods_desc | +----+------+------+------------+-----------
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我这里创建了一个 goods 表，先看下里面的数据： 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、根据s_id分组 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 | +----+------+------+------------+-------------+------------+------------------+---------------+-------+----------------+ 这里使用了 group_concat()函数，主要目的是为了显示分组的详细信息 上面的根据单个字段分组很简单，把相同s_id的记录都归组了 2、根据s_id,goods_desc字段分组 分析：这里查询分组时，会先根据s_id分组，然后对每个组里面的数据再根据goods_desc进行分组 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 | +----+------+------+------------+-------------+------------+------------------+-------------+------+--------------+ 这里的goods_descs 和 上面的一比较就明白了 接下来还可以再根据 goods_price 分组 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 | +----+------+------+------------+-------------+------------+-------------+-------------+------+--------------+ GROUP BY X, Y意思是将所有具有相同X字段值和Y字段值的记录放到一个分组里。 （编辑：威海站长网） 【声明】本站内容均来自网络，其相关言论仅代表作者个人观点，不代表本站立场。若无意侵犯到您的权利，请及时与联系站长删除相关内容! |
