Question

整个查询：

SELECT NULL, 
ELT( MOD( A.contact_id, (SELECT count(*) FROM  `ak_contact` WHERE  `contact_type_id` = 12) )+1, (SELECT  CONCAT( "'",GROUP_CONCAT(CAST(contact_id  AS CHAR(7)) SEPARATOR "','"),"'"  )  FROM  `ak_contact` WHERE  `contact_type_id` = 12) ) as operator_id,
B.account_id, A.contact_id, A.email
FROM ak_contact A
JOIN ak_accounts B USING (contact_id)
GROUP BY A.email, A.contact_id, B.account_id
ORDER BY A.contact_id DESC

子查询应该为每行逐个选择ID 10493,10495,11262,11800,12362,13405中的一个：

ELT( MOD( A.contact_id, (SELECT count(*) FROM  `ak_contact` WHERE  `contact_type_id` = 12) )+1, (SELECT  CONCAT( "'",GROUP_CONCAT(CAST(contact_id  AS CHAR(7)) SEPARATOR "','"),"'"  )
#result: ELT(MOD(3333, 5)+1, '10493','10495','11262','11800','12362','13405')

问题是我无法强制使用子查询来处理ELT（A.contact_id，子查询）。或者我如何制作这样的东西：

ELT(MOD(3333, 5)+1, '10493','10495','11262','11800','12362','13405')

在主查询中

Answer 1

你可以使用FIND_IN_SET和一个子查询，它使用GROUP_CONCAT以逗号分隔的字符串'10493,10495,11262，...'传递所有值。

（但请注意，GROUP_CONCAT可以返回的字符串大小受服务器配置的限制。）

Answer 2

MySQL 8表格，您可以使用：

WITH
cte1 AS (
   SELECT
      (MOD( A.contact_id, (SELECT count(*) FROM  ak_contact WHERE  contact_type_id = 12) )+1)mx,
      B.account_id,
      A.contact_id,
      A.email
   FROM ak_contact A
      INNER JOIN ak_accounts B USING (contact_id)
GROUP BY A.email, A.contact_id, B.account_id
), 
cte2 AS (
   SELECT
      (ROW_NUMBER() OVER ())mx,
      CAST(contact_id  AS CHAR(7))cid
   FROM ak_contact
   WHERE contact_type_id = 12
)
SELECT cte1.*, cte2.*
FROM cte1
LEFT JOIN cte2 ON cte1.mx = cte2.mx
ORDER BY cte1.contact_id DESC;

ELT（）带子查询而不是参数

2 个答案: