W/O using OOABAP

plzz help me giving all the possible ways with explanation to do the following :------

i dont want the database table to use regularly, so i created 3 internal tables from which i want to extract data & put those data in the main output table which is used in ALV.

the 3 internal tables are linked thru primary keys.....but want other fields to be extracted thru primary-foreign key relationship.

how should i bring the data from the the 3 internal tables into the output internal table ?

<u><b>W/O using OOABAP.</b></u>