mysql - PHP 查询不起作用

Question

这正在工作:

SELECT *
FROM ((((defect
JOIN project_testcase ON 
defect.Test_Id=project_testcase.Test_Id)
JOIN testcase ON 
defect.Test_Id=testcase.Test_Id)
JOIN project_pm ON 
project_testcase.Project_Id=project_pm.Project_Id)
JOIN employee ON 
employee.Emp_id=project_pm.Emp_id)

但是，这不起作用:

SELECT *
FROM ((((defect
JOIN project_testcase ON 
defect.Test_Id=project_testcase.Test_Id)
JOIN testcase ON 
defect.Test_Id=testcase.Test_Id)
JOIN project_pm ON 
project_testcase.Project_Id=project_pm.Project_Id)
JOIN employee ON 
employee.Emp_id=project_pm.Emp_id)
WHERE Project_Id LIKE '%$categ%'

因为我使用了 JOIN 表并使用 Project_Id 进行连接。这是错误吗？

Answer 1

要解决此问题，我要做的第一件事是将其粘贴到 SQL 格式化程序中。这将有助于查找语法错误并可以帮助您查看逻辑错误。我会推荐freeformatter.com .

其次，你可以去掉括号。

修复

您需要指定在 WHERE 中获取 Project_Id 的表，因为它位于多个表中，但为了清楚起见，我将始终指定它来自哪个表。

select
   *   
from
   defect   
join
   project_testcase         
      on   defect.Test_Id=project_testcase.Test_Id       
join
   testcase      
      on   defect.Test_Id=testcase.Test_Id    
join
   project_pm   
      on   project_testcase.Project_Id=project_pm.Project_Id    
join
   employee   
      on   employee.Emp_id=project_pm.Emp_id    
where
   project_testcase.Project_Id like '%$categ%'