Question

以下查询引发错误：

SELECT * FROM proposal_data
  INNER JOIN proposal_data
      ON proposal_data_second.proposal_id = proposal_data.proposal_id

  INNER JOIN proposal_data_second   
      ON proposal_data_third.proposal_id =  proposal_data_second.proposal_id
  INNER JOIN proposal_data_third
      ON proposal_data_fourth.proposal_id = proposal_data_third.proposal_id

错误是：

#1066 - Not unique table/alias: 'proposal_data'

我做错了什么？

Answer 1

你错误地加入了表格。

在当前查询中，您在声明之前加入表格：

e.g。先前三行

SELECT * FROM proposal_data
  INNER JOIN proposal_data
      ON proposal_data_second.proposal_id = proposal_data.proposal_id

此处，您在宣布proposal_data表格之前加入proposal_data_second proposal_data_second。

此外，您不需要两次使用表名peoposal_data：

SELECT * FROM proposal_data
  INNER JOIN proposal_data --This is invalid syntax

试试这个：

SELECT * FROM proposal_data
   INNER JOIN proposal_data_second
           ON proposal_data_second.proposal_id = proposal_data.proposal_id
   INNER JOIN proposal_data_third
           ON proposal_data_third.proposal_id = proposal_data_second.proposal_id
   INNER JOIN proposal_data_fourth
           ON proposal_data_fourth.proposal_id = proposal_data_third.proposal_id

有关详情，请参阅MySQL: JOIN Syntax

多个表JOIN抛出'不唯一的表/别名'错误

1 个答案: