[[No Subject]]

Correct, inner joins in an update statement are violations of the SQL
standard and are not supported by PostgreSQL. The following link
explains correct syntax that can be used with an update statement:

http://www.postgresql.org/docs/9.0/static/sql-update.html
If it isn't very good, do you have any suggestions on how it can be improved?


--SQL compliant syntax
UPDATE public_consumption_hanson_uk_el_clear AS A
SET acutal_estimate
= ( SELECT MIN( C.actual_estimate ) AS minimum_actual_estimate
FROM public_consumption_hanson2 AS C
WHERE C.supply_day = A.supply_day
AND C.supply_brand_name = A.supply_brand_name
AND C.meter_no = A.meterreference
AND C.mpan = A.meterpiontreference ) AS B(
minimum_actual_estimate );

--Postgresql extension syntax
UPDATE public_consumption_hanson_uk_el_clear AS A
SET acutal_estimate = B.minimum_actual_estimate
FROM ( SELECT supply_day, supply_brand_name, meter_no, mpan,
MIN( C.actual_estimate ) AS minimum_actual_estimate
FROM public_consumption_hanson2 AS C
GROUP BY supply_day, supply_brand_name, meter_no ) AS B
WHERE B.supply_day = A.supply_day
AND B.supply_brand_name = A.supply_brand_name
AND B.meter_no = A.meterreference
AND B.mpan = A.meterpiontreference ;