php - MySQL查询不从哪里条件中获取数据

我已经编写了一个MySQL查询？我想从中获取数据t.taskid = b.id OR t.taskid = '0' AND t.subtaskid = j.id OR t.subtaskid = '0'，但条件对此不起作用

SELECT t.id as id
     , t.taskid
     , t.subtaskid
     , p.PNAME AS projectname
     , t.date AS DATE
     , b.Summary AS tasks
     , j.SUMMARY AS subtasks
     , t.mon AS time1
     , t.tue AS time2
     , t.wed AS time3
     , t.thu AS time4
     , t.fri AS time5
     , t.sat AS time6
     , t.sun AS time7
  FROM bt_createissue b
     , bt_createissue j
     , timesheet t
  LEFT
  JOIN bt_project p
    ON t.projectid = p.pkey
 WHERE t.taskid = b.id
    OR t.taskid = 0
   AND t.subtaskid = j.id
    OR t.subtaskid = 0
   AND t.date >= '2015-03-09'
   AND t.date <= '2015-03-30'
   AND t.username = '$username'

最佳答案

如果要加入t.taskid = b.idt.subtaskid = j.id，请检查是否可以修改

WHERE t.taskid = b.id OR t.taskid = '0'AND t.subtaskid = j.id OR t.subtaskid = '0'

以上行有适当的联接。
因为在where子句中使用联接条件可以创建交叉联接而不是预期的交叉联接。

如果不起作用

尝试使用having clause代替where clause，并且不要忘记使用group by