Question

Hi I am just learning SQL and i am trying to retrieve some data from multiple tables and cannot get it to display how I would like it, so i am just wondering if this is possible or not, and if so could someone suggest a method, see below:

    Table1:                     Table2:                     Table3

    Package       Licenses      Package       Licenses      Package      Licenses
    ======================      ======================      =====================
    Product1         20         Product1         15         Product1        0
    Product2         15         Product2         5          Product2        5
    Product3         10         Product3         10         Product3        0

I would like the values in the Licenses columns to be added to each other according to the package name and it to display something like this if possible:

    Package       Licenses
    ======================
    Product1         35
    Product2         25
    Product3         20

If someone could let me know how this could be done, if such a thing is even possible please let me know.

Answer 1

Try this:

SELECT Package, SUM(Licences) as TotalLicences
  FROM (
        SELECT Package, Licences FROM Table1
         UNION ALL
        SELECT Package, Licences FROM Table2
         UNION ALL
        SELECT Package, Licences FROM Table3
       ) AS AllLicences
 GROUP BY Package