In the ThinkPHP5 framework, there are many ways to query whether it is empty. This article will introduce several commonly used methods.

1. Query using the where method

The where method is one of the commonly used query methods in the ThinkPHP5 framework. By passing in an array, you can query whether the specified field is empty. The code is as follows:

//?查詢name字段是否為空
$user?=?db('user')->where('name',?'null')->find();
if?($user)?{
????echo?'name字段不為空';
}?else?{
????echo?'name字段為空';
}

2. Query using field method

The field method is also one of the commonly used query methods in the ThinkPHP5 framework. By passing in the query field name and conditions, you can query whether the specified field is empty. The code is as follows:

//?查詢name字段是否為空
$user?=?db('user')->field('name')->where('name',?'null')->find();
if?($user)?{
????echo?'name字段不為空';
}?else?{
????echo?'name字段為空';
}

3. Use the select method to query

The select method can also query whether the specified field is empty. By passing in the query conditions and field name, if the query result is empty, it means that the field is empty. The code is as follows:

//?查詢name字段是否為空
$user?=?db('user')->where('name',?'null')->select();
if?($user)?{
????echo?'name字段不為空';
}?else?{
????echo?'name字段為空';
}

4. Use the query method to query

The query method can execute native SQL statements. Query whether the specified field is empty by using MySQL's is null or is not null keywords. The code is as follows:

//?查詢name字段是否為空
$user?=?db()->query("SELECT?*?FROM?`user`?WHERE?`name`?IS?NULL");
if?($user)?{
????echo?'name字段為空';
}?else?{
????echo?'name字段不為空';
}

The above are several methods of querying whether it is empty introduced in this article. When using it, you can choose the method that suits you according to the actual situation.

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