如何检查MySQL是否返回null/empty? [英] How to check if MySQL returns null/empty?

问题描述

在DB中，我有一个表，其中有一个名为fk_ownerID的字段.默认情况下，当我添加新表行时，fk_ownerID为空.在MySQL的Toad中，这显示为{null}.如果为fk_ownerID提供了一个值，然后我删除了该值，则设置为fk_ownerID = "".

In DB I have a table with a field called fk_ownerID. By default, when I add a new table row, the fk_ownerID is empty. In Toad for MySQL, this is shown as {null}. If fk_ownerID is given a value, and I later remove this value, I set fk_ownerID = "".

现在，我有以下代码:

$result = $dal->getRowByValue('tableName','id', $_POST['myID']);

// Check to see if any rows where returned
if (mysql_num_rows($result) > 0)
{
  while ($row = mysql_fetch_array($result))
  {
    $ownerID = $row["fk_ownerID"];    
  }
}

现在变量$ ownerID应该有一个数字，否则就没有.但我不确定如何检查.目前，我正在这样做:

Now the variable $ownerID should have a number, or not. But I'm unsure how to check this. Currently I'm doing this:

if ( (strlen($ownerID) == 0) || ($ownerID == '0') || ($ownerID == 'null') )

但是我很确定这些测试中只有一项是必要的.

But I'm pretty sure only one of these tests should be necessary.

检查行字段为空还是空的最佳方法是什么?

What is the best way to check if a row field is empty or null?

推荐答案

使用empty()和/或is_null()

Use empty() and/or is_null()

http://www.php.net/empty 单独使用空就可以实现当前的用法，如果要区分空字段和空字段，is_null只会使更多的控制成为可能.

Empty alone will achieve your current usage, is_null would just make more control possible if you wanted to distinguish between a field that is null and a field that is empty.

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