Join

Join

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In the context of computing, a “join” is commonly associated with database operations, specifically in Structured Query Language (SQL). A join operation combines rows from two or more tables, based on a related column between them, into a new table. This operation is crucial for querying relational databases, where data is organized into separate tables with relations defined between them.

There are several types of join operations:

  1. Inner Join: Also known as a simple join, it returns records that have matching values in both tables involved in the join.
  2. Left (Outer) Join: Returns 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 right side.
  3. Right (Outer) Join: Returns 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 left side.
  4. Full (Outer) Join: Returns all records when there is a match in either the left or the right table.

Joins provide the ability to fetch complex data sets in a single query, leveraging the relational nature of the database, reducing the need for multiple queries and enhancing performance.

Note: In other computing contexts, the term “join” can have different meanings. For example, in concurrent programming, a “join” operation often involves waiting for a thread to finish execution.

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