Update statement with nested joins not working - mysql

Question

I need to update multiple records in a table based upon the sum of some values in another table. Here is my query:
UPDATE aallinnot2 c SET c.Energ_Kcal = ( SELECT d.id1, SUM( c.Energ_Kcal)
FROM aaingred a
LEFT JOIN aaweight b ON a.unit = b.uni
LEFT JOIN aallinnot2 c ON a.mfdfsds = c.NDB_No
LEFT JOIN aalinfsds d ON a.fsdsnum = d.id1
WHERE d.own_id =42
GROUP BY id1 )
WHERE c.NDB_No
IN ( SELECT DISTINCT `fsdsnum`
FROM `aaingred`
WHERE `usernum` LIKE '42'
)
MySQL said:
#1093 - You can't specify target table 'c' for update in FROM clause
Unfortunately, I don't know how to get my values without referencing target table 'c'! Is there a workaround for this?

Answer 1

With the crazy table/column names and indecipherable logic, this might be the ugliest query I have ever seen. Congrats. :)
I think the following should work (or this approach). The main problem was untangling the group-by expression-- you need to give the database engine a dataset where each row in the target table is joined to a set that contains the updated value for that row. So here, select the new values in a sub-query, then join that sub-query to the original table.
EDIT Fixed some syntax
UPDATE
(
SELECT d.id1, SUM (c.Energ_Kcal) AS Sum_Energ_Kcal
FROM aaingred a
LEFT JOIN aaweight b ON a.unit = b.uni
LEFT JOIN aallinnot2 c ON a.mfdfsds = c.NDB_No
LEFT JOIN aalinfsds d ON a.fsdsnum = d.id1
WHERE d.own_id =42
GROUP BY id1
) d
,aaingred a, aallinnot2 d
SET Energ_Kcal = d.Sum_Energ_Kcal
WHERE d.id1 = a.fsdsnum
AND a.mfdfsds = aallinnot2.NDB_No
AND c.NDB_No IN (
SELECT DISTINCT `fsdsnum`
FROM `aaingred`
WHERE `usernum` LIKE '42'
);

Answer 2

I'm not sure about mysql, but with SQL Server the statement would be something like this:
UPDATE aallinnot2
SET Energ_Kcal = (
SELECT SUM( c.Energ_Kcal)
FROM aaingred a
LEFT JOIN aaweight b ON a.unit = b.uni
LEFT JOIN aallinnot2 c ON a.mfdfsds = c.NDB_No
LEFT JOIN aalinfsds d ON a.fsdsnum = d.id1
WHERE d.own_id =42)
WHERE c.NDB_No
IN ( SELECT DISTINCT `fsdsnum`
FROM `aaingred`
WHERE `usernum` LIKE '42')
You can't alias the table to be updated in the UPDATE clause, but you can in the FROM clause.