Question

我有像这样的mysql查询

SET @sql = NULL;
SELECT

  GROUP_CONCAT(
      'fvalue AS ',x.name
  ) INTO @sql

from reimbursment x
LEFT JOIN reimbursment_limit y
ON y.acc_code = x.acc_code;

SET @sql = CONCAT('SELECT b.firstname, ', @sql, ' from user b
left join reimbursment_limit c
  on b.id = c.user_id
left join reimbursment d
  on c.acc_code = d.acc_code
group by b.id');

PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;

和这样的表，

用户

id nip    firstname
1  123456 AAAAA
2  999999 BBBBB

reimbursment

id acc_code name
1  22002    Dentis
2  22004    Allowance

报销限额

id user_id acc_code fvalue
1  1       22002    500000
2  1       22004    700000

和结果，像这样

firstname Dentis Allowance
AAAAA     500000 500000
BBBBB     null   null

正确的结果，必须

firstname Dentis Allowance
AAAAA     500000 700000
BBBBB     null   null

这个查询是workig，但是没有给出正确的结果，其中用户AAAAA的余量必须为700000，如何修复结果？我已尝试任何但仍然没有给出正确的结果。

谢谢

Answer 1

问题在于加入小组

SET @sql = CONCAT('SELECT b.firstname, ', @sql, ' from user b
left join reimbursement c -- swapped join clause
  on b.id = c.user_id
left join reimbursment_limit d
  on c.acc_code = d.acc_code'); -- removed group by

SQLFiddle

动态Mysql查询不给出正确的结果

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