SQL JOINS

There are six types of SQL Joins, and they are:

1. Inner Join: Also called as Join. It returns the rows present in both the Left table, and right table only if there is a match. Otherwise, it returns zero records.
2. Full Outer Join: Also called as Full Join. It returns all the rows present in both the Left table, and right table.
3. Left Outer join: Or simply called as Left Join. It returns all the rows present in the Left table and matching rows from the right table (if any).
4. Right Outer Join: Also called as Right Join. It returns matching rows from the left table (if any), and all the rows present in the Right table.
5. Self Join: It is used to Join the table with itself. We can use this technique to calculate Running Total etc.
6. Cross Join: It is used to return the Cartesian product of two tables. It means, Number of rows in Employees multiplied by Number of rows in Department table

In this article we will show you, How to write a SQL Query to Join two or more tables using the SQL Joins with example. This is one of the SQL Server Frequently Asked Question. For this example, We are going to use the below shown data

Data present in the Department Table is:

SQL JOINS Example

Before we get into the practical example, Let us see the visual representation of the Inner Join, Full Outer Join, Left Outer join, Right Outer Join, Self Join, and Cross Join for better understanding.

SQL Joins Example – Inner Join

In this example we will show you, How to write an Inner Join in SQL Server. For this, We are going to use the Employee and Department tables that we shown above. We had already explained the Inner Join in our previous article so, I suggest you to refer them for better understanding

--SQL Server JOINS :- Example for SQL INNER JOIN 
USE [SQLTEST]
GO
SELECT Emp.[EmpID]
      ,Emp.[FirstName]
      ,Emp.[LastName]
      ,Emp.[Education]
      ,Emp.[YearlyIncome]
      ,Emp.[Sales]
	  ,Dept.[DepartmentName]
  FROM [Employees] AS Emp
  INNER JOIN [Department] AS Dept
  ON Emp.DeptID = Dept.DeptID

OUTPUT

SQL Joins Example – Left Join

In this example we will show you, How to write a Left Outer Join, or Left Join in SQL Server. For this, We are going to use the tables that we shown above. We had already explained the Left Join in our previous article so, I suggest you to refer them for better understanding

--SQL Server JOINS :- Example for SQL LEFT JOIN, or SQL LEFT OUTER JOIN 
USE [SQLTEST]
GO
SELECT Emp.[EmpID]
      ,Emp.[FirstName]
      ,Emp.[LastName]
      ,Emp.[Education]
      ,Emp.[YearlyIncome]
      ,Emp.[Sales]
	  ,Dept.[DepartmentName]
  FROM [Employees] AS Emp
  LEFT JOIN [Department] AS Dept
  --LEFT OUTER JOIN [Department] AS Dept
  ON Emp.DeptID = Dept.DeptID

OUTPUT

SQL Joins Example – Right Join

In this example we will show you, How to write a Right Outer Join, or Right Join in SQL Server. For this, We are going to use the tables that we shown above. We had already explained the Right Join in our previous article so, I suggest you to refer them for better understanding

--SQL Server JOINS :- Example for RIGHT JOIN, or RIGHT OUTER JOIN 
USE [SQLTEST]
GO
SELECT Emp.[EmpID]
      ,Emp.[FirstName]
      ,Emp.[LastName]
      ,Emp.[Education]
      ,Emp.[YearlyIncome]
      ,Emp.[Sales]
	  ,Dept.[DepartmentName]
  FROM [Employees] AS Emp
  RIGHT JOIN [Department] AS Dept
  --RIGHT OUTER JOIN [Department] AS Dept
  ON Emp.DeptID = Dept.DeptID

OUTPUT

SQL Joins Example – Full Join

In this example we will show you, How to write a Full Outer Join, or Full Join in SQL Server. For this, We are going to use the tables that we shown above. We had already explained the Full Join in our previous article so, I suggest you to refer them for better understanding

--SQL Server JOINS :- Example for FULL JOIN 
USE [SQLTEST]
GO
SELECT Emp.[EmpID]
      ,Emp.[FirstName]
      ,Emp.[LastName]
      ,Emp.[Education]
      ,Emp.[YearlyIncome]
      ,Emp.[Sales]
	  ,Dept.[DepartmentName]
  FROM [Employees] AS Emp
  FULL JOIN [Department] AS Dept
    --FULL OUTER JOIN [Department] AS Dept
  ON Emp.DeptID = Dept.DeptID

OUTPUT

SQL Joins Example – Self Join

In this example we will show you, How to write a Self Join in SQL Server. We had already explained the Self Join in our previous article so, I suggest you to refer them for better understanding

--SQL Server JOINS :- Example for SELF JOIN 
USE [SQLTEST]
GO
SELECT Emp.[EmpID]
      ,Emp.[FirstName]
      ,Emp.[LastName]
      ,Emp.[Education]
      ,Emp.[YearlyIncome]
      ,Emp.[Sales]
	  ,NewEmp.[YearlyIncome]  + 25000 AS [New Income]
  FROM [Employees] AS Emp, [Employees] AS NewEmp
  WHERE Emp.EmpID = NewEmp.EmpID

OUTPUT

SQL Joins Example – Cross Join

In this example we will show you, How to find a Cartesian Product using Joins, or simply Cross Join in SQL Server. For this, We are going to use the tables that we shown above. We had already explained the Cross Join in our previous article so, I suggest you to refer them for better understanding

--SQL Server JOINS :- Example for SQL CROSS JOIN 
USE [SQLTEST]
GO
SELECT Emp.[EmpID]
      ,Emp.[FirstName]
      ,Emp.[LastName]
      ,Emp.[Education]
      ,Emp.[YearlyIncome]
      ,Emp.[Sales]
      ,Dept.[DepartmentName]
  FROM [Employees] AS Emp
  CROSS JOIN [Department] AS Dept

OUTPUT

SQL Joins Example – Multiple Joins

Data Present in the LogInTable is as shown below

In this example we will show you, How to use the Multiple Joins in one SELECT Statement. For this, We are going to use the Inner Join, and Left Join on tables that we shown above.

--SQL Server JOINS :- Example for Multiple JOIN 
USE [SQLTEST]
GO
SELECT Emp.[EmpID]
      ,Emp.[FirstName]
      ,Emp.[LastName]
      ,Emp.[Education]
      ,Emp.[YearlyIncome]
      ,Emp.[Sales]
	  ,logg.USERNAME
	  ,Dept.[DepartmentName]
  FROM [Employees] AS Emp
  INNER JOIN [Department] AS Dept
  ON Emp.DeptID = Dept.DeptID
  LEFT JOIN [LogInTable] AS logg
  ON Emp.EmpID = logg.LogID

OUTPUT

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