Question

i have two tables a_daily and o_daily_lcsgeneration:

i am trying this query :

update a_daily
set
  a_daily.Turbine_Generation =  
   (
     select sum(o_daily_lcsgeneration.Turbine_Generation) 
     from o_daily_lcsgeneration 
     where o_daily_lcsgeneration.Location = 1 
     group by o_daily_lcsgeneration.Date
  ) 

but received the above error saying sub query more than 1 row

Answer 1

remove the GROUP BY clause

UPDATE a_daily
SET a_daily.Turbine_Generation = 
(
        SELECT sum(o_daily_lcsgeneration.Turbine_Generation)
        FROM o_daily_lcsgeneration
        WHERE o_daily_lcsgeneration.Location = 1
)

it causes the query to return more than one value of you have multiple dates.

UPDATE 1

UPDATE  a_daily a
        INNER JOIN
        (
            select g.Date, sum(g.Turbine_Generation) totalSum
            from o_daily_lcsgeneration g
            where g.Location = 1 
            group by g.Date
        ) b ON a.date = b.date
SET     a.Turbine_Generation = b.totalSum
WHERE       a.location = 1

or

UPDATE  a_daily a
        LEFT JOIN JOIN
        (
            select g.Date, sum(g.Turbine_Generation) totalSum
            from o_daily_lcsgeneration g
            where g.Location = 1 
            group by g.Date
        ) b ON a.date = b.date
SET     a.Turbine_Generation = COALESCE(b.totalSum, 0)