* refactor: clean to roadmap content * refactor: move shared helpers into scripts/lib
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Self Join
A self join is a query in SQL that joins a table to itself. This is useful when you want to compare rows within the same table, often based on a hierarchical relationship or other connection between the data points within that table. Think of it as creating two copies of the same table and then joining them based on a shared column, allowing you to relate data from the same source in a new way.
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