PHP isset() method ignores data error handling caused by null parameter value

During the process of writing a script to export database data , The data is not quite right , Check the cause , It is found that... Is used in logical judgment isset() Method , However, there are some problems in the data queried from the database NULL value , Cause error .

for example ：

$a = array('name' => NULL); 

var_dump(isset($a['name'])); // false

This may cause some data to be skipped or mishandled . There are many solutions , For example, value advance string processing , Or add additional conditions or the default value of database field settings is not allowed to be NULL etc. , No more details here .