Table Update Related issues

Table Update problem!
Both tables contain serial numbers, device type fields.
I now want to update table two device type value for table one the same serial number device type value, ask how to write?

------Solution--------------------
$sql = ' SELECT * from table 2 ';
$res = mysql_query ($sql) or Die (' Query failed: '. mysql_error ());
while ($row = Mysql_fetch_array ($res)) {
$sql 1 = "SELECT * FROM table 1 where serial number = $row [' Serial number '] limit 1";
$res 1 = mysql_query ($sql 1) or Die (' Query failed: '. mysql_error ());
while ($row 1 = mysql_fetch_array ($res)) {
$sql 2 = "Update table 2 set Device Type value = $row 1[' device type value '] where serial number = $row [' Serial number ']";
mysql_query ($sql 2);
}
}
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That's probably what it means. Change it yourself.

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