MYSQL update clause comparing the WHERE from 2 tables

$produpd = "UPDATE tblnavpc SET tblnavpc.ChildName = tblnav.NavName " .
    "FROM tblnav WHERE tblnavpc.CID = tblnav.NavID";

This is the error I get"

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'FROM tblnav WHERE tblnavpc.CID = tblnav.NavID' at line 1

I know keys aren't named greatly but I just trying to fix this one problem, I didn't 开发者_开发问答name the tables.

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You don't have a FROM clause in an update:

UPDATE tblnavpc
INNER JOIN tblnav ON tblnavpc.CID = tblnav.NavID
SET tblnavpc.ChildName = tblnav.NavName

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"From" cannot be used with update statements. Should be

$produpd = "UPDATE tblnavpc SET tblnavpc.ChildName = tblnav.NavName " .
    "WHERE tblnavpc.CID = tblnav.NavID";