集团通过部分字符串

Question

这里是我的表：

----------+-----------+-------------- 
45678-sm-w| 18  | Mens clothing 
----------+-----------+-------------- 
45678-sm-b| 5  | Mens clothing 
----------+-----------+-------------- 
2189-L-Wh | 4  | Juniors Clothing 
----------+-----------+-------------- 
2189-L-Bl | 3  | Juniors Clothing 
----------+---------- +-------------- 

这是期望的结果是什么：

----------+-----------+-------------- 
45678  | 23  | Mens clothing 
----------+-----------+-------------- 
2189  | 7  | Juniors Clothing 
----------+-----------+-------------- 

Answer 1

你可以改变表？它将使最有意义的分裂col1三个栏（如id，size，并且color）修改表，让你可以通过新的id栏目组：

-----+----+----+-----------+-------------- 
45678| sm | w | 18  | Mens clothing 
-----+----+----+-----------+-------------- 
45678| sm | b | 5  | Mens clothing 
-----+----+----+-----------+-------------- 
2189 | L | Wh | 4  | Juniors Clothing 
-----+----+----+-----------+-------------- 
2189 | L | Bl | 3  | Juniors Clothing 
-----+----+----+---------- +-------------- 

你可以做到这一点使用ALTER TABLE添加所需的三列并更改主键，使用SUBSTRING_INDEX和UPDATE提取并存储拆分值，并使用另一个ALTER TABLE进行清理。事情是这样的：

ALTER TABLE t 
DROP PRIMARY KEY; 

ALTER TABLE T 
ADD id INT UNSIGNED NOT NULL, 
ADD size VARCHAR(255), 
ADD color VARCHAR(255), 
ADD PRIMARY KEY (col1); 

UPDATE TABLE t 
SET id = CONVERT(SUBSTRING_INDEX(col1, '-', 1), UNSIGNED INTEGER), 
SET size = SUBSTRING_INDEX(col1, '-', 2), 
SET color = SUBSTRING_INDEX(col1, '-', 3); 

ALTER TABLE t 
DROP COLUMN col1; 

---

如果你不能改变的表，你可以提取需要使用SUBSTRING_INDEX ID号：

SELECT SUBSTRING_INDEX(col1, '-', 1), col2, col3 FROM table; 

给出：

-----+-----------+-------------- 
45678| 18  | Mens clothing 
-----+-----------+-------------- 
45678| 5  | Mens clothing 
-----+-----------+-------------- 
2189 | 4  | Juniors Clothing 
-----+-----------+-------------- 
2189 | 3  | Juniors Clothing 
-----+---------- +-------------- 

对于最终查询，我会使用一个SELECT来提取您需要的id，以及一个外部SELECT分组：

SELECT id, SUM(col2) AS total, col3 
FROM 
    (SELECT SUBSTRING_INDEX(col1, '-', 1) AS id, col2, col3 
    FROM table) AS t 
GROUP BY id 

Answer 2

CAST第一列数字，添加一个索引到新创建的列并在该列上按总和运行一个组。

update table set `left`=CAST(col1 AS SIGNED); 

select `left`,sum(*),`col3` from table; 

Answer 3

如果您选择的数据，那么你可以使用这样的事情：

select SUBSTRING_INDEX(col1, '-', 1) col1, 
    sum(col2) Total, 
    col3 
from table1 
group by SUBSTRING_INDEX(col1, '-', 1), SUBSTRING_INDEX(col3, ' ', 1) 
order by col1 desc 

见SQL Fiddle With Demo