MySQL的工作不IS NOT NULL

Question

所以我有以下查詢

query = "SELECT date_format(startPeriod,'%a, %M, %d, %Y') as startDate, 
      date_format(startTime,'%I:%i%p') as startTime, 
      date_format(endTime,'%I:%i%p') as endTime, 
      jobLocation,jobId, 
       hoursWorked 
     FROM users,paycheck 
     WHERE users.userId = '" . $_SESSION['userId'] . 
     "' AND userId = empId 
     AND startPeriod IS NOT NULL 
     ORDER BY paycheck.startPeriod DESC"; 

的問題是，一些startPeriod的值（這是一個日期）爲null所以，當我跑我的查詢我不想以顯示那些爲空的日期，但不幸的是，日期是空的顯示在我的表上。我怎樣才能解決這個問題？

這是我的源

<tr><td></td><td>12:00AM</td><td>12:00AM</td><td>none</td><td>none</td><td>0.00</td></tr> 

我的輸出文件的第一TDS之間，你可以看到它的空

Answer 1

你確定插入的數據實際上是空的，而不是隻是一個空字符串？

之後更換startPeriod IS NOT NULL到TRIM(startPeriod) <> ""

OR

query = "SELECT date_format(startPeriod,'%a, %M, %d, %Y') as startDate, 
      date_format(startTime,'%I:%i%p') as startTime, 
      date_format(endTime,'%I:%i%p') as endTime, 
      jobLocation,jobId, 
       hoursWorked 
     FROM users,paycheck 
     WHERE users.userId = '" . $_SESSION['userId'] . 
     "' AND userId = empId 
     AND (startPeriod != '0000-00-00' OR startPeriod IS NOT NULL) 
     ORDER BY paycheck.startPeriod DESC"; 

這可能幫助你。