the purpose of using mapping load is to drop one field of one table to other table
for this in two tables you have must one primary key then using mapping load,
load 1st field which is primary key to both table and through that field load another field which you want to drop it in another table while execution...
the concept of mapping table is that,
the mapped table(table1) have atleast two column(field name), 1st column must be primary key and on the basis of it we mapped the 2nd column from table2.
primary key must be common in both table.
productname from table1;
Applymap('table1',productid) as productname
hope this helps you.