We need a data table, when we do Statistics , Multi-Variable Analysis , Data Mining and Process Analysis for Reasoning .
If all data is in the relational database, we relate the data. And we get a data table.
But such case is not general. We need skills and techniques to join data and make tables.
By the way, in many cases of my experience, analysis is completed when I analyze only spreadsheet software. It is a powerful tool of analysis.
When we link data, we make new electric data. Because we use meta-knowledge and experience when we link data. Without difficult methods such as Multi-Variable Analysis and Data Mining , we may discover great conclusion after linking.
I call "one vs many" if a side has same value and the other side has various data. In this situation, there are two ways.
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