如何在MySQL查詢CONCAT，GROUP_CONCAT，按多子查詢

Question

我有數據庫結構和數據：

id | total | type | value_1 | value_2 
1 | 9 | 1 | 10 | 20 
2 | 9 | 1 | 21 | 30 
3 | 10 | 1 | 31 | 40 
4 | 9 | 2 | 41 | 50 
5 | 9 | 2 | 51 | 60 
6 | 8 | 2 | 61 | 70 

請幫助我如何查詢這樣的結果呢？

type || total || id ||  value 
1 || 9|10 || 1,2|3 || 10-20,21-30|31-40 
2 || 9|8 || 4,5|6 || 41-50,51-60|61-70 

Answer 1

這應該一旦你改變表名。訣竅是分階段構建它。首先，合併value_1和value_2，然後按總數分組，然後使用,作爲分隔符，最後按|分組。

select type, 
group_concat(distinct total separator '|') as total, 
group_concat(distinct id separator '|') as id, 
group_concat(distinct vals separator '|') as vals 
from (select type, 
    group_concat(distinct total separator ',') as total, 
    group_concat(distinct id separator ',') as id, 
    group_concat(distinct vals separator ',') as vals, 
    count(id) as count 
    from (select id, total, type, concat(value_1,'-',value_2) as vals from tbl) as a 
    group by total, type order by count desc) as b 
group by type; 

我複製你的表，所以我可以測試出來

mysql> select * from tbl; 
+------+-------+------+---------+---------+ 
| id | total | type | value_1 | value_2 | 
+------+-------+------+---------+---------+ 
| 1 |  9 | 1 |  10 |  20 | 
| 2 |  9 | 1 |  21 |  30 | 
| 3 | 10 | 1 |  31 |  40 | 
| 4 |  9 | 2 |  41 |  50 | 
| 5 |  9 | 2 |  51 |  60 | 
| 6 |  8 | 2 |  61 |  70 | 
+------+-------+------+---------+---------+ 
6 rows in set (0.00 sec) 

下面是結果。

mysql> select type, 
-> group_concat(distinct total separator '|') as total, 
-> group_concat(distinct id separator '|') as id, 
-> group_concat(distinct vals separator '|') as vals 
-> from (select type, 
-> group_concat(distinct total separator ',') as total, 
-> group_concat(distinct id separator ',') as id, 
-> group_concat(distinct vals separator ',') as vals, 
-> count(id) as count 
-> from (select id, total, type, concat(value_1,'-',value_2) as vals from tbl) as a 
-> group by total, type order by count desc) as b 
-> group by type; 
+------+-------+-------+-------------------+ 
| type | total | id | vals    | 
+------+-------+-------+-------------------+ 
| 1 | 9|10 | 1,2|3 | 10-20,21-30|31-40 | 
| 2 | 9|8 | 4,5|6 | 41-50,51-60|61-70 | 
+------+-------+-------+-------------------+ 
2 rows in set, 1 warning (0.00 sec)