有3个表，需要在第3个表中插入两个表的主键作为外键

Question

<?php

$user_id = mysql_insert_id();
$sql = "INSERT INTO personcase(pcId,pId,docketNo,pType) VALUES ('','$user_id','(SELECT MAX(case.docketNo)FROM case)','C');";
$res = mysql_query($sql) or die(mysql_error());

?>