This document discusses different types of joins in SQL including inner joins, natural joins, left outer joins, and right outer joins. It provides the syntax for each type of join and examples of queries using employee data from emp and emp1 tables. Key details covered include how natural joins form a cartesian product and remove duplicate columns, and that left/right outer joins return all records from one table and matched records from the other table.

1. Database system
concept
JOINED RELATION

2. PREPARED BY
Ms.M.Raihana Begum -III-B.Sc - Information Technology
UNDER THE GUIDANCE OF
Mrs.P.Anusha M.Sc(IT).,M.Phil.,D.P.T.T.,(Ph.D).,
Assistant professor,
Department of Information Technology,
Bon secours college for women,
Thanjavur.

3. Select * from emp;

4. Select * from emp1;

5. JOIN:
A join clause is used to combine rows
from two or more tables, based on a
related column between them.
QUERY:
Select * from table1 join table2;

7. NATURAL JOIN
• The natural join operation forms a cartesian
product of its two arguments, performs selection
forcing equality on those attributes that appear in
both relation schema a finally remove duplicate
attributes.
QUERY:
Select * from table 1 natural join table 2;

8. Example
Select * from emp natural join emp1;

9. Select * from empfull;

10. Select * from emppartime;

11. INNER JOIN
Returns record that have matching values in both the
table.
QUERY:
Select table1.colum_name from table1 inner join
table2 on table1.column_name=table2.column_name

12. • Example:
select empfull.name form empfull innerjoin emppartime on
empfull.emp_id=emppartime.emp_id;

13. LEFT OUTER JOIN
• Returns all records from the left table, and the
matched records from the right table.
QUERY:
Select table name1. column name from table
name1 left join on table name2.column
name=table name2.column name;

14. • EXAMPLE:
Select empfull.name from empfull left join
emppartime on empfull.emp_id=emppartime.emp_id;

15. RIGHT OUTER JOIN
• Returns all records from the right table, and the
matched records from the left table.
QUERY:
Select table name1.column name from table
name1 right join table name2 on table
name1.column name=table name2.column name

16. EXAMPLE:
Select empfull.name from empfull right join emppartime on
empfull.emp_id = emppartime.emp_id;