Сумма из разных таблиц

mysql_query("UPDATE `ask1` SET `fed` =`abz1.fed` + `alsh1.fed` FROM abz1, alsh1");
$result = mysql_query("SELECT  fed FROM ask1");
$result = mysql_fetch_assoc($result);

CREATE TABLE `abz1` (
    `fed` VARCHAR(64), 
    PRIMARY KEY(`uid`)
);
CREATE TABLE `alsh1` (
    `fed` VARCHAR(64), 
    PRIMARY KEY(`uid`)
);
CREATE TABLE `ask1` (
    `fed` VARCHAR(64), 
    PRIMARY KEY(`uid`)
);
);

SELECT SUM(fld1)
FROM
(
SELECT fld1
FROM tab1
 
UNION ALL
 
SELECT fld1
FROM tab2
)

UPDATE tbl1100
SET fld100 = (<здесь указанный SELECT>)

$summm = mysql_query("SELECT SUM(fed)
FROM ask1
(
SELECT fed
FROM abz1
 
UNION ALL
 
SELECT fed
FROM alsh2
)");
$result = mysql_query("SELECT fed FROM ask1");
$result = mysql_fetch_assoc($result);

mysql_select_db($db);
$sum = mysql_query("UPDATE ask1
SET fed = (SELECT SUM(fed)
FROM
(
SELECT fed
FROM abz1
 
UNION ALL
 
SELECT fed
FROM alsh1
))");
$result = mysql_query("SELECT fed FROM ask1");
$result = mysql_fetch_assoc($result);

UPDATE aks1
SET ask1.fed = (SELECT SUM(fed) 
FROM
(
SELECT fed
FROM abz1
 
UNION ALL
 
SELECT fed
FROM alsh1
))

SELECT fed
FROM abz1 T1   -- T1 - это алиас для таблицы abz1