How to SUM two fields within an SQL query

SUM is an aggregate function. It will calculate the total for each group. + is used for calculating two or more columns in a row.

Consider this example,

ID  VALUE1  VALUE2
===================
1   1       2
1   2       2
2   3       4
2   4       5

SELECT  ID, SUM(VALUE1), SUM(VALUE2)
FROM    tableName
GROUP   BY ID

will result

ID, SUM(VALUE1), SUM(VALUE2)
1   3           4
2   7           9

SELECT  ID, VALUE1 + VALUE2
FROM    TableName

will result

ID, VALUE1 + VALUE2
1   3
1   4
2   7
2   9

SELECT  ID, SUM(VALUE1 + VALUE2)
FROM    tableName
GROUP   BY ID

will result

ID, SUM(VALUE1 + VALUE2)
1   7
2   16