在MySql中修改通过group_Concat获得的值？

Question

我有以下 [table 个]

id     res1     res2     

1       a        f
1       b        f
1       b        f
1       c        f
2       e        g 
2       e        g
2       e        g
2       f        g

我在执行 group_concat

后得到以下信息

select 
  id, 
  group_concat(case when cnt = 1 then res1 else concat(cnt, ' ', res1) end) as r1,
  group_concat(case when cnt = 1 then res2 else concat(cnt, ' ', res2) end) as r2

from 
(
  select id, res1,res2, count(*) as cnt
  from [table a]
  group by id, res1,res2
) t
group by id;


id      r1          r2

1      a,2 b,c     f,2 f,f
2      3 e,f       3 g,g

res1 列正常，但 res2 列复制了 res1 列。基本上我想打印一个字符在字符之前出现多少次的值。 .我想要以下格式..

id     r1          r2

1      a,2 b,c     4 f
2      3 e,f       4 g

如何实现？

Answer 1

我的方法是执行两个 rollups/aggregations，对 res1 和 res2 列使用两个单独的子查询。第一个聚合在 id 和 res1（或 res2）上，并获得每个字母或单词的计数。然后，再次聚合，这次只聚合 id，以获得每个 id 的逗号分隔字符串。最后将这些子查询拼接起来得到最终的结果。

SELECT
    t1.id, t1.r1, t2.r2
FROM
(
    SELECT t.id, GROUP_CONCAT(res1agg ORDER BY res1) AS r1
    FROM
    (
        SELECT
            id,
            res1,
            CASE WHEN COUNT(*) = 1 THEN res1
                 ELSE CONCAT(CAST(COUNT(*) AS CHAR(50)), res1) END AS res1agg
        FROM yourTable
        GROUP BY id, res1
    ) t
    GROUP BY t.id
) t1
INNER JOIN
(
    SELECT t.id, GROUP_CONCAT(res2agg ORDER BY res2) AS r2
    FROM
    (
        SELECT
            id,
            res2,
            CASE WHEN COUNT(*) = 1 THEN res2
                 ELSE CONCAT(CAST(COUNT(*) AS CHAR(50)), res2) END AS res2agg
        FROM yourTable
        GROUP BY id, res2
    ) t
    GROUP BY t.id
) t2
    ON t1.id = t2.id;

输出：

此处演示：

Rextester

Answer 2

刚刚在您的查询中添加了 2 个条件，而没有使用更多的内部查询。

试试这个：-

input:-

CREATE TABLE Table1 (id INT, res1 varchar(20), res2 varchar(20));
insert into Table1  values(1, 'a', 'f');
insert into Table1  values(1, 'b', 'f');
insert into Table1  values(1, 'b', 'f');
insert into Table1  values(1, 'c', 'f');
insert into Table1  values(2, 'e', 'g');
insert into Table1  values(2, 'e', 'g');
insert into Table1  values(2, 'e', 'g');
insert into Table1  values(2, 'f', 'g');

Query:-


 Select t.id,group_concat(case when cnt = 1 then res1 else concat(cnt, ' ', res1) end) as r1,
 case when id=1 then trim(concat(sum(case when id = 1 then cnt end),' ',res2)) 
 else trim(concat(sum(case when id = 2 then cnt end),' ',res2)) end as r2
 from
 (
  select id, res1,res2,count(*) as cnt
  from table1 a
  group by id, res1,res2
 ) t
 group by t.id

My Output:-
    id  r1        r2
    1   a,c,2 b  4 f
    2   f,3 e    4 g

如果您有任何问题，请告诉我

在MySql中修改通过group_Concat获得的值？

modify the values achieved through group_Concat in MySql?

mysql

sql

group-concat

Rextester