Arithmetic overflow on column sum in sql server

问题

I'm trying to get a column total but when i run this query i get the following error. Any advice?

SELECT SUM(Size) as total
FROM  AllDocs
Where DirName LIKE 'sites/test/test%'


ERROR:
Msg 8115, Level 16, State 2, Line 1
Arithmetic overflow error converting expression to data type int.
Warning: Null value is eliminated by an aggregate or other SET operation.

回答1:

While all your sizes can fit into INT (up to 2^31 - 1), their SUM cannot.

Cast them into BIGINT:

SELECT  SUM(CAST(Size AS BIGINT)) as total
FROM    AllDocs
WHERE   DirName LIKE 'sites/test/test%'

来源：https://stackoverflow.com/questions/1222877/arithmetic-overflow-on-column-sum-in-sql-server