This is working:
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)
However, this does not work:
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%'
As I have used JOIN tables and joined using Project_Id. Is that the error?
$categis a variable, in which case you should concatenate it's value, now you just use its name ('%' + $categ + '%'). If you can, use prepared statements, which is much better still.