我的INSERT语句有什么问题？ （PHP）[重复]

I am trying to execute this INSERT statemente but it isn't executed. I echoed the $query string and it seems ok. When attempting to execute with mysqli_query($connect, $query) nothing happens, just a blank screen.

$query = "INSERT INTO spservices('service_no', 'service_email', 'service_type', 'service_exit_node', 'service_billing', 'service_next_due', 'service_download', 'service_password') 
VALUES('$serviceNo','$mail', '$serviceType', '$enode', '$serviceBilling','$nextDue','Pending until payment confirmed','$servicePass')";

if (mysqli_query($connect, $query)) {
    //MY CODE SENDS AN EMAIL HERE
}

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Strings with single quotes are considered as user inputs not table/field names in SQL.

So, the corrected SQL:

$query       = "INSERT INTO spservices(service_no, service_email, service_type, service_exit_node, service_billing, service_next_due, service_download, service_password) 
VALUES('$serviceNo','$mail', '$serviceType', '$enode', '$serviceBilling','$nextDue','Pending until payment confirmed','$servicePass')";

Instead of single quotes in field names, you can use backtick operator

(`) around column/field names.

This is useful when your field name is exactly a reserved SQL word.

For example.

SELECT `select` FROM users