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Relational Databases

“JOIN” is an SQL keyword used to query data from two or more related tables.

Inner join (or just Join)

The most frequently used clause is INNER JOIN. This produces a set of records which match in both the user and course tables.

Left join

This produces a set of records which matches every entry in the left table regardless of any matching entry in the right table.

Learning Resources

  • Here is a nice youtube tutorial.
  • Understanding JOINs in MySQL and Other Relational Databases article.