Difference Between Inner Join And Full Join In SQL Server

Introduction

In this article, I am going to explain the difference between Inner join and full join with examples. This is one of the very common SQL server interview questions.

Here we will be using SQL Server 2017 or you can use SQL Server 2008 or above.

Read my previous Joins in SQL Server 2017 part of this article using the below links before reading this article,

Definition of Joins

It is used to fetch/retrieve data from two or more related tables from the database. In general, tables are related to each other using foreign key constraints.

Prerequisites

SQL Server 2017 or you can use SQL server 2008 or above version.

Now, first we will create a Database and two tables to apply the joins for understanding.

Creating Database and Two Tables

Step 1 - Create a Database

Open your SQL Server and use the following script to create the “chittadb” Database.

Create database chittadb

Now, select the script query then press F5 or click on Execute button to execute the above script.

You should see a message, “Command(s) completed successfully.” It means your new database is created.

Step 2 - Create first table

Open your SQL Server and use the following script to create table “tbl_Department”.

create table tbl_Department
(
DeptId int primary key not null identity(1,1),
DeptName nvarchar(50),
DeptHead nvarchar(50),
Location nvarchar(100)
)

Execute the above query to create “tbl_Department “.

You should see a message, “Command(s) completed successfully.”

Now, data has been inserted into the table.

Insert into tbl_Department values ( 'IT', 'Chitta', 'Chennai')
Insert into tbl_Department values ( 'Payroll', 'Akhil', 'Odisha')
Insert into tbl_Department values ( 'HR', 'Ram', 'Pune')
Insert into tbl_Department values ( 'Timesheet', 'Kannan', 'chennai')

Execute the above query, you should see a message, “Command(s) completed successfully.”

Now retrieve all data from “tbl_Department” table.

select * from tbl_Department

output

Difference Between Inner Join And Full Join In SQL Server

Step 3 - Create second table

Open your SQL Server and use the following script to create table “tbl_Employee”.

Create table tbl_Employee
(
EmpID int primary key not null identity(1,1),
Name nvarchar(50),
Gender nvarchar(50),
country nvarchar(20),
Salary int,
DepartmentId int foreign key references tbl_Department(DeptId)
)

Execute the above query to create “tbl_Employee “.

You should see a message, “Command(s) completed successfully.”

Now, data has been inserted into the table.

Insert into tbl_Employee values ( 'Jitu', 'Male','India',4000, 1)
Insert into tbl_Employee values ( 'Rani', 'Female','India', 5000, 3)
Insert into tbl_Employee values ( 'Rohit', 'Male','India', 5500, 1)
Insert into tbl_Employee values ( 'Dibas', 'Male','India', 6500, 2)
Insert into tbl_Employee values ( 'Gajendra', 'Male','India', 3800, 2)
Insert into tbl_Employee values ( 'Raja', 'Male','India', 9000, 1)
Insert into tbl_Employee values ( 'Jeni', 'Female','India', 5800, 3)
Insert into tbl_Employee values ( 'Chandin', 'Female','India', 8500, 1)
Insert into tbl_Employee values ( 'pintu', 'Male','India', 9500, NULL)
Insert into tbl_Employee values ( 'Subrat', 'Male','India', 9800, NULL)

Execute the above query, you should see a message, “Command(s) completed successfully.”

Now retrieve all data from “tbl_Employee” table.

select * from tbl_Employee

output

General Formula for Joins

SELECT ColumnList (whatever column you want to display)
FROM LeftTableName
JOIN_TYPE RightTableName
ON JoinCondition

INNER JOIN

Inner join returns only the matching rows between both the tables, non matching rows are eliminated.

Example

Write a query to retrieve Name, Gender Country, Salary and DeptName from tbl_Employee and tbl_Department table.

INNER JOIN Query

SELECT Name, Gender,country, Salary, DeptName
FROM tbl_Employee
INNER JOIN tbl_Department
ON tbl_Employee.DepartmentId = tbl_Department.DeptId

SELECT Name, Gender,country, Salary, DeptName
FROM tbl_Employee
JOIN tbl_Department
ON tbl_Employee.DepartmentId = tbl_Department.DeptId

Note

JOIN or INNER JOIN means both are the same. It's always better to use INNER JOIN.

select emp.Name,emp.Gender,emp.country,emp.Salary,dept.DeptName
from tbl_Employee emp
inner join tbl_Department dept
on emp.DepartmentId=dept.DeptId

OutPut

FULL JOIN or FULL OUTER JOIN

Full Join or Full Outer Join returns all rows from both the tables (left & right tables), including non-matching rows from both the tables.

Example

Write a query to retrieve Name, Gender, Country, Salary and DeptName from tbl_Employee and tbl_Department table.

FULL JOIN or FULL OUTER JOIN Query

SELECT Name, Gender,country, Salary, DeptName
FROM tbl_Employee
FULL OUTER JOIN tbl_Department
ON tbl_Employee.DepartmentId = tbl_Department.DeptId

SELECT Name, Gender,country, Salary, DeptName
FROM tbl_Employee
FULL JOIN tbl_Department
ON tbl_Employee.DepartmentId = tbl_Department.DeptId

Note

You can use, FULL JOIN or FULL OUTER JOIN. OUTER keyword is optional.

select emp.Name,emp.Gender,emp.country,emp.Salary,dept.DeptName
from tbl_Employee emp
FULL JOIN tbl_Department dept
on emp.DepartmentId=dept.DeptId

OutPut

What is the difference between INNER JOIN and FULL JOIN

INNER JOIN

Inner join returns only the matching rows between both the tables, non-matching rows are eliminated.

FULL JOIN

Full Join or Full Outer Join returns all rows from both the tables (left & right tables), including non-matching rows from both the tables.

What is the Difference between INNER JOIN and JOIN

There is no difference between inner join and join, they are exactly the same. Similarly there is also no difference between

LEFT JOIN and LEFT OUTER JOIN
RIGHT JOIN and RIGHT OUTER JOIN
FULL JOIN and FULL OUTER JOIN

Conclusion

In this article, I explained the difference between inner join and full join in SQL Server with examples. I hope this article has helped you to understand this topic. Post your valuable feedback in the comments section.