Unions are used to combine the result set of two or more
data sources.
Let us consider a scenario where we need combine two set of
test details of the student. We have two tables , one with internal test
details and another with final test. And we are going use union node to combine
these two tables.(If you are having common records in two projection then we will get two records in union - Union in HANA act as UNION ALL function)
Below are the tables which we are going to combine.
Click on the Auto Map By Name icon for mapping the source field
names to target.
Similar to other nodes we can create calculated column, use
input parameters and rename the field names.
After mapping the source fields, add all fields to the
output and activate the view.
Now we can find the both data combined in the final data
preview.
Note: If you are having same records with measure in two projection and we are using union node then we will get two records in union. The Measure value would be doubled. To avoid the doubling issue what we can do is
1. Create calculated column CA_FLAG1 and CA_FLAG2 in each projection with 'X' in calculated column
2. Add Aggregation node on top of the union and bring all fields
3. Then create another calculated for measure if CA_FLAG1='X' and CA_FLAG2 = 'X' then measure/2(handle if you are having 0 in measure)else same measure. This will solve our doubling issue in union node
