Question

我正在使用Moodle数据库。我不希望在我的查询中显示任何NULL值。但到目前为止它还没有起作用：

SELECT mdl_user.department, mdl_user.id, mdl_user.username, mdl_user.firstname, mdl_user.lastname, mdl_course_completions.course, mdl_course_completions.timecompleted, mdl_course.fullname  

FROM mdl_user LEFT JOIN (mdl_course_completions, mdl_course) ON (mdl_user.id = mdl_course_completions.id AND mdl_course_completions.id = mdl_course.id) WHERE NOT (mdl_course_completions.timecompleted IS NULL);\G
Empty set (0.00 sec)

我尝试使用IS NOT NULL，但这给了我相同的结果。

任何想法???

Answer 1

这是我或多或少的期望：

<div id="store_map">
  <div class="gm_popup">
    <span class="address"> Address</span><br>
    <span class="city"> City</span><br>
    <span class="phone"> 123 456</span><br>
    <span class="email"> email@example.com</span><br>
</div>

</div>


jQuery(document).ready(function(){



  focus_and_popup = function (id){
    //return_val = old_focus_and_popup (id);


      jQuery("#store_map .gm_popup .email").click(function(){
        var text = jQuery(this).text();
        console.log("HERE");
        document.location = "mailto:" + text.trim();
      });

      jQuery(".gm_popup .email").css('text-decoration','underline').css('color','#2aa8e0');

    return return_val ;
  }
  focus_and_popup();
   var old_focus_and_popup = focus_and_popup;
});

假设SELECT mdl_user.department, mdl_user.id, mdl_user.username, mdl_user.firstname, mdl_user.lastname, mdl_course_completions.course, mdl_course_completions.timecompleted, mdl_course.fullname FROM mdl_user LEFT JOIN mdl_course_completions ON mdl_user.id = mdl_course_completions.user_id LEFT JOIN mdl_course ON mdl_course_completions.course_id = mdl_course.id) WHERE mdl_course_completions.timecompleted IS NOT NULL有外键mdl_course_completions到user_id和mdl_user(id)到course_id。

Answer 2

SELECT 
    mdl_user.department, 
    mdl_user.id, 
    dl_user.username,
    mdl_user.firstname, 
    mdl_user.lastname, 
    mdl_course_completions.course,
    mdl_course_completions.timecompleted, 
    mdl_course.fullname  
FROM mdl_user
LEFT JOIN (SELECT * FROM mdl_course_completions WHERE timecompleted IS NOT NULL) as mdl_course_completions
    ON mdl_user.id = mdl_course_completions.user_id 
LEFT JOIN mdl_course 
    ON mdl_course_completions.id = mdl_course.id

正如其他用户建议的那样，＆＃34; mdl_user.id = mdl_course_completions.id＆＃34;看起来并不正确＆＃34; user_id = user_id＆＃34;我假设mdl_course_completions的id不是用户的id？

无法在MYSQL中过滤NULLS

2 个答案: