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Asked: 2025-04-25T18:18:34+05:30 In:

What is a JOIN in SQL?

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      In SQL, a JOIN is a means for combining columns from one or more tables based on a related column between them. This allows you to query data from multiple tables as if the data were contained in one table. Joins are essential for querying and analyzing data that is spread across different tables in relational databases. The primary purpose of a JOIN is to identify and create relationships between tables based on a matching column, typically involving primary and foreign keys.

      The main types of JOINs in SQL include:

      1. INNER JOIN: Selects records that have matching values in both tables involved in the join. It returns the intersection of the two tables.

      2. LEFT JOIN (or LEFT OUTER JOIN): Selects all records from the left table, and the matched records from the right table. If there is no match, the result is NULL on the side of the right table.

      3. RIGHT JOIN (or RIGHT OUTER JOIN): Selects all records from the right table, and the matched records from the left table. If there is no match, the result is NULL on the side of the left table.

      4. FULL JOIN (or FULL OUTER JOIN): Combines LEFT JOIN and RIGHT JOIN, returning all records when there is a match in either left or right table. If there is no match, the result is NULL on the side without a match.

      5. CROSS JOIN: Produces a Cartesian product of the two tables, i.e.,

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