What is a Join? List its different types.

1.	What is a Join? List its different types.
Answer» The SQL Join clause is used to combine RECORDS (rows) from two or more tables in a SQL database based on a related column between the two. There are four different TYPES of JOINs in SQL: (INNER) JOIN: Retrieves records that have matching values in both tables involved in the join. This is the WIDELY used join for queries. SELECT FROM Table_AJOIN Table_B;SELECT FROM Table_AINNER JOIN Table_B; LEFT (OUTER) JOIN: Retrieves all the records/rows from the left and the matched records/rows from the right table. SELECT FROM Table_A ALEFT JOIN Table_B BON A.col = B.col; RIGHT (OUTER) JOIN:* Retrieves all the records/rows from the right and the matched records/rows from the left table. SELECT FROM Table_A ARIGHT JOIN Table_B BON A.col = B.col; FULL (OUTER) JOIN:* Retrieves all the records where there is a match in either the left or right table. SELECT *FROM Table_A AFULL JOIN Table_B BON A.col = B.col;

Answer»

The SQL Join clause is used to combine RECORDS (rows) from two or more tables in a SQL database based on a related column between the two.

There are four different TYPES of JOINs in SQL:

(INNER) JOIN: Retrieves records that have matching values in both tables involved in the join. This is the WIDELY used join for queries.

SELECT *FROM Table_AJOIN Table_B;SELECT *FROM Table_AINNER JOIN Table_B;

LEFT (OUTER) JOIN: Retrieves all the records/rows from the left and the matched records/rows from the right table.

SELECT *FROM Table_A ALEFT JOIN Table_B BON A.col = B.col;

RIGHT (OUTER) JOIN: Retrieves all the records/rows from the right and the matched records/rows from the left table.

SELECT *FROM Table_A ARIGHT JOIN Table_B BON A.col = B.col;

FULL (OUTER) JOIN: Retrieves all the records where there is a match in either the left or right table.

SELECT *FROM Table_A AFULL JOIN Table_B BON A.col = B.col;

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