Wednesday, June 17, 2009

The different types of joins in oracle database

The different types of joins in oracle database:
Joins are used to produce the single data set output from multiple tables based on requirement to get matched records or mismatched records.
the different types of joins we can see in oracle database and one can write joins in either ANSI/ISO or SQL92 standard and both will work on 9i later version of oracle database systems.

I found interesting in writing of join conditions as joins drives the entire query efficient execution and returns output in best optimized way. one can use join concepts in best possible way to get desired results in faster way.

These are the joins one can see oracle database and will explain one by one.

Self joins
Inner joins
Equi-joins
non equi-joins
Outer joins
Cross joins
Anti-joins
Semi-joins

Self Joins:
As we know it is a joining of table itself and we can say table is joined or compared to itself. This table name appears twice in the FROM clause of select statement and followed by table aliases to qualify the column names in the join condition.

Example:


Inner join:
An inner join is a join of more than two tables that returns all those rows that satisfy the given join condition.

Equi-joins

non equi-joins

Outer joins

Cross joins

Anti-joins

Semi-joins

-- more yet to come...
----- Have a fun in working in Oracle Technologies-- Cheers--

No comments:

Post a Comment