SQL Joins

  SQL   Wednesday, July 9, 2014   7648 | No Comments Yet!!! | No Download | No Demo | Pawan Kumar
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SQL Joins

SQL joins are used to get rows from one or more than two tables.

Different SQL JOINs are:-

  1. INNER JOIN: Returns all rows when there is at least one match in BOTH tables
  2. LEFT JOIN: Return all rows from the left table, and the matched rows from the right table
  3. RIGHT JOIN: Return all rows from the right table, and the matched rows from the left table
  4. FULL JOIN: Return all rows when there is a match in ONE of the tables

SQL INNER JOIN

The INNER JOIN is used to selects all rows from both tables as long as there is a match between the columns in both tables.

SQL INNER JOIN Syntax

         
            SELECT column-name(s)
            FROM table-one
            INNER JOIN table-two
            ON table-one.column-name=table-two.column-name;
            

or:

            SELECT column-name(s)
            FROM table-one
            JOIN table-two
            ON table-one.column-name=table-two.column-name;
            

SQL LEFT JOIN

The LEFT JOIN used to returns all rows from the left table (table-one), with the matching rows in the right table (table-two). The result is NULL in the right side when there is no match.

SQL INNER JOIN Syntax

            SELECT column-name(s)
            FROM table-one
            LEFT JOIN table-two
            ON table-one.column-name=table-two.column-name;
            

or:

            SELECT column-name(s)
            FROM table-one
            LEFT OUTER JOIN table-two
            ON table-one.column-name=table-two.column-name;
            

SQL RIGHT JOIN

The RIGHT JOIN keyword used to get all rows from the right table (table-two), with the matching rows in the left table (table-one). The result is NULL in the left side when there is no match.

SQL RIGHT JOIN Syntax

            SELECT column-name(s)
            FROM table-one
            RIGHT JOIN table-two
            ON table-one.column-name=table-two.column-name;
            

or:

            SELECT column-name(s)
            FROM table-one
            RIGHT OUTER JOIN table-two
            ON table-one.column-name=table-two.column-name;
            

SQL FULL OUTER JOIN

The FULL OUTER JOIN keyword used to get all rows from the left table (table-one) and from the right table (table-two).

The FULL OUTER JOIN keyword combines the result of both LEFT and RIGHT joins.

SQL FULL OUTER JOIN Syntax

            SELECT column-name(s)
            FROM table-one
            FULL OUTER JOIN table-two
            ON table-one.column-name=table-two.column-name;
            

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