php 在 Laravel 数据库查询中处理空值？
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Dealing with null values in Laravel database query?
提问by Hailwood
I am finding that I often need to select a field, based on a condition other than the id.
我发现我经常需要根据 id 以外的条件选择一个字段。
So, $user = User::where('last_login', $lastLogin)->where('last_warning', $lastWarning)->get();works perfectly.
所以，$user = User::where('last_login', $lastLogin)->where('last_warning', $lastWarning)->get();工作完美。
That is until you set one of the where's to allow nulls (let's do last_login).
直到您设置允许空值的位置之一（让我们做last_login）。
That is, it can either have a value or be null.
也就是说，它可以有一个值，也可以为空。
That means you need to use one of two function where()or whereNull()and to do that you need to break the chain, so it becomes
这意味着您需要使用两个功能之一，where()或者whereNull()要做到这一点，您需要打破链条，因此它变成
$user = User::where('last_warning', $lastWarning);
is_null($lastLogin) ? $user->whereNull('last_login') : $user->where('last_login', $lastLogin);
$user = $user->get();
I am wondering if wherehas a way to deal with this? as currently if you pass nullthrough to where you get where column = nullwhich doesn't work!
我想知道是否where有办法解决这个问题？就像目前一样，如果您null通过到您到达的地方where column = null，则不起作用！
回答by Laurence
Two options:
两种选择：
Option 1:
选项1：
if (is_null($lastLogin))
{
$user = User::whereNull('last_login')->where('last_warning', $lastWarning)->get();
}
else
{
$user = User::where('last_login', $lastLogin)->where('last_warning', $lastWarning)->get();
}
Option 2:
选项 2：
$user = User::where('last_login', (is_null($lastLogin) ? 'IS' : '=') ,$lastLogin)->where('last_warning', $lastWarning)->get();
Option two makes the query 'where last_login = x'or 'where last_login IS null'
选项二使查询 'where last_login = x'或 ' where last_login IS null'
回答by André Luiz Müller
You can try this:
你可以试试这个：
User::where(function($query) use ($lastlogin)
{
if(is_null($lastLogin))
{
$query->whereNull('last_login');
}
else
{
$query->where('last_login', '=', $lastLogin);
}
})->get();
It is a good solution when dealing with long queries with more than one parameter.
在处理具有多个参数的长查询时，这是一个很好的解决方案。
回答by Marco Aurélio Deleu
As of Laravel 5.3 you are now able to ->where('column', null)to automatically produce WHERE column IS NULL.
从 Laravel 5.3 开始，您现在可以->where('column', null)自动生成WHERE column IS NULL.
If using variable, make sure that they have PHP nullstrict value.
如果使用变量，请确保它们具有 PHPnull严格值。
回答by Gabriel Koerich
You can use DB::raw() as well:
您也可以使用 DB::raw() ：
User::where('last_login', 'IS', DB::raw('null'))->where_last_warning($lastWarning)->get();
