通过另一个表中的列更新SQL Server 2008 R2中的表，并且还需要求和值

Question

I am trying to update a table in SQL Server 2008 R2.

Table1:

   id  name  value1
   a    34     3
   a    32     2
   a    -      - 
   c    90      9

Table2:

  id 
  a

expected table1:

   id  name  value1
   a    34     3
   a    32     2
   a    -      5 
   c    90      9

I need to sum all value1 group by id that exists in table2.

My SQL query:

 update table1
 set value1 = cast(SUM(cast ([value1] as float)) as varchar(50))
 GROUP BY id
 where name = '-' and id in 
 (  
    select distinct id
    from table2
  ) 

I got error:

Incorrect syntax near the keyword 'GROUP'.

Any help would be appreciated.

UPDATE

 update table1
 set value1 = cast(SUM(cast ([value1] as float)) as varchar(50))
 where name = '-' and id in 
 (  
    select distinct id
    from table2
  ) 
 GROUP BY id

still :

Incorrect syntax near the keyword 'GROUP'.

Answer 1

You can't use that construct afaik. You need a subquery to calculate your values based on id, and update from that table:

UPDATE table1
    SET value1 = SumTable.val
FROM (  
        SELECT T1.id, cast(SUM(cast (T1.[value1] as float)) as varchar(50)) as val
        FROM    table1 T1
        WHERE T1.id in 
             (  
                select distinct T2.id
                from table2 T2
              ) 
        GROUP BY T1.id
    ) AS SumTable
WHERE   table1.id = SumTable.id

Answer 2

If you just want to return the grouped result, you can do this by running the following

SELECT ID, SUM(Value) 
FROM Table1 
WHERE ID IN (SELECT ID FROM Table2) GROUP BY ID

If, however, you want to replace the contents of table1, there's no trivial way of doing this in a single operation. You need 'cache' the intermediate result before recreating the original table:

DECLARE @TEMPTABLE TABLE (ID int, Value int);

INSERT INTO @TEMPTABLE SELECT ID, SUM(Value) 
FROM Table1 
WHERE ID IN (SELECT ID FROM Table2) GROUP BY ID

DROP TABLE Table1

SELECT * INTO Table1 FROM @TempTable

SELECT * FROM TABLE1

(note, that was from your first edit)

If you just want to add additional 'sum' lines to the table, then you should be able to avoid the temp table and instead issue an INSERT INTO statement using the SELECT statement I gave first as a sub-query.

I do think what you're doing is quite strange, however, and you may want to think about what you're doing with your tables.

Your casting back to a VARCHAR is also a little strange - if they're always going to be an integer, keep them as integers. If they're truly VARCHARS then SUM won't always work