将新创建的id值作为外键插入另一个表的列中

Hello everyone PHP and mysql noob here

I'm creating a form to create a new user and at the same time add a contact
but user and contact are in two different table

and i need the newly user_ID to reference the user_ID(FK) in the tbl_contact

how would i do it?

first of all insert the user

mysql_query("INSERT INTO tbl_user (...) VALUES (...)");

then retrieve the last inserted id

$LIid=mysql_insert_id();

then insert the contact with this id

mysql_query("INSERT INTO tbl_contact (user_ID,...) VALUES ($LIid,...)");

Refrence

If you want to use mysqli

$mysqli->query("INSERT INTO tbl_user (...) VALUES (...)");
$LIid=$mysqli->insert_id;
$mysqli->query("INSERT INTO tbl_contact (user_ID,...) VALUES ($LIid,...)");