Join in SQL Server: Part 1

Join:

Join clause use to combine the data from one and more than one table.. Suppose there is a company in this company there is more than 2 departments and management people of this company would like to display the data from both table at a time. In this case back end developer we will be create one join. For better understanding we will create two tables as EmployeeDetails and Department in database like.

create table Empdetails
    (
        eid int Primary key,ename varchar(20),Designation varchar(20),Salary int
    )
create table Department
    (
        Did int,DName varchar(20),eid int foreign key references Empdetails(eid)
    )

Inserting values in Database

Insert into Empdetails values
    (
        1,’Sandeep’,’S/w Dev.’,25000
    )
Insert into Department values
    (
        101,’Development’,1
    )

                        Figure: EmployeeDetails table

 
                       Figure: Department table

Now back end developer will be create one joins by using following syntax.

Syntax:

Select columns name
From Left side table name
Joins type Right side table name
On condition

Sample Example :

select ename,Designation,did,dname
from EmpDetails
inner join Department
on EmpDetails.eid=department.eid

Above view Query will display the data as,

   
                                    Figure: JoinsData

Point to Remember: Joins clause use to combined the data from one and more than one tables. There are types of Joins and these are: 

1. Inner Join
2. Left outer join
3. Right outer join
4. Cross join

Syntax for join

Select column name
From table name//Left side table name
Join type table name//Right side table name
On condition

Sample Example for join

select ename,Designation,did,dname
from EmpDetails //EmpDetails is left side table
inner join Department // Department is Right side table
on EmpDetails.eid=department.eid