Question

I have a table with two columns. Items in the first column represent one of four categories, and items in the second column represent the data referenced by their category counterpart:

CategoryA : 2
CategoryC : 1
CategoryB : 4
CategoryB : -1
CategoryD : 2
CategoryC : 1

etc.

I need to construct a SQL query that will return the Sum for each of these categories, e.g.

CategoryA : 2
CategoryB : 3
CategoryC : 2
CategoryD : 2

Answer 1

You can do it by grouping together the relevant rows, and summing the values for each:

select col1, sum(col2)
  from table_name
group by col1