DATABASE MANAGEMENT SYSTEM
Joins in SQL
SQL JOINS
As the name shows, JOIN means to combine something. In case of SQL, JOIN means "to
combine two or more tables".
In SQL, JOIN clause is used to combine the records from two or more tables in a database.
Types of SQL JOIN
1.INNER JOIN
2.LEFT JOIN
3.RIGHT JOIN
4.FULL JOIN
DATABASE MANAGEMENT SYSTEM
Joins in SQL
SQL JOINS
1. INNER JOIN
In SQL, INNER JOIN selects records that have matching values in both tables as
long as the condition is satisfied. It returns the combination of all rows from
both the tables where the condition satisfies.
Syntax: SELECT table1.column1, table1.column2, table2.column1,..
FROM table1 INNER JOIN table2 ON table1.matching_column = table2.matching_column;
DATABASE MANAGEMENT SYSTEM
Joins in SQL
SQL JOINS
2. LEFT JOIN
The SQL left join returns all the values from left table and the matching values
from the right table. If there is no matching join value, it will return NULL.
Syntax: SELECT table1.column1, table1.column2, table2.column1,.... FROM table1
LEFT JOIN table2 ON table1.matching_column = table2.matching_column;
DATABASE MANAGEMENT SYSTEM
Joins in SQL
SQL JOINS
3. RIGHT JOIN
In SQL, RIGHT JOIN returns all the values from the values from the rows of right
table and the matched values from the left table. If there is no matching in both
tables, it will return NULL.
Syntax:
SELECT table1.column1, table1.column2, table2.column1,.... FROM table1 RIGHT JOIN table2
ON table1.matching_column = table2.matching_column;
DATABASE MANAGEMENT SYSTEM
Joins in SQL
SQL JOINS
4. FULL JOIN
In SQL, FULL JOIN is the result of a combination of both left and right outer join.
Join tables have all the records from both tables. It puts NULL on the place of
matches not found.
Syntax:
SELECT table1.column1, table1.column2, table2.column1,.... FROM table1 FULL JOIN table2
ON table1.matching_column = table2.matching_column;
DATABASE MANAGEMENT SYSTEM
Joins in SQL
SQL JOINS- EXERCISE
Try out all types of joins on the given data tables.
EMPLOYEE PROJECT
Emp_id Emp_na City Salary Age
me Emp_id Project_no Department
101 Akash New York 1500 29 101 1261 Mechanical
102 Sanjay Citadel 1800 32 103 1853 Operations
103 Mathew Los 2600 38 104 1097 Automation
Angeles 105 1857 Development
104 Thomas New York 2000 26
105 Regina New 1900 30
Jersey
