Data source (Merge)

An overview of how to merge data sources to create a single mammoth data source

This data source is formed by merging two or more data sources (Join) using the concept of UNIONS. This data source (Merge) is a bigger pool compared to the data source (Join). The data columns in the respective data sources assemble and provide a visual summary of the collective data in the form of rows and columns based on the Union Type.

What are Unions?

The Union clause is used to combine two separate data sources (i.e., result-sets of joined data tables) and produce a mammoth result-set as a union of both the data sources. There are two scenarios to apply the Unions concept: 

1. The fields to be used in both the data sources must be in the same order, same number, and same data type. 
2. The Union clause produces distinct values in the result set. To fetch the duplicate values, UNION ALL must be used instead of just UNION. 

A sneak peek into the experience of merging data sources with Union All clause to create an advanced data source, is provided in the GIF below.