Different types of joins in DBMS with examples?

Answer 1

Inner Join-: It is also called simple join. It returns all rows from both tables if there is any match.

SELECT * FROM R1, R2 WHERE R1.r1_field = R2.r2_field; SELECT * FROM R1 INNER JOIN R2 ON R1.field = R2.r2_field

Natural Joins -: it is used when two tables have all columens with same name

Left [Outer] Join -: Returns all rows from table 1 even if there is no match in table 2, all mismatch will be printed as null

Right [Outer] Join -: Returns all rows from table 2 even if there is no match in table 1, all mismatch will be printed as null

Cross Join -:This type of join is rarely used as it does not have a join condition, so every row of table 1 is joined to every row of table 2. For example, if both tables contain 100 rows the result will be 10,000 rows. This is sometimes known as a cartesian product and can be specified in either one of the following ways:

SELECT * FROM table 1 CROSS JOIN table2

SELECT * FROM table1, table2

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