SQL Joins
SQL joins are used to combine rows from two or more tables.
SQL JOIN
An SQL JOIN clause is used to combine rows from two or more tables, based on a common field between them.
The most common type of join is SQL INNER JOIN (simple join). An SQL INNER JOIN returns all rows from multiple tables where the join condition is met.
Let's look at a selection from the "Orders" table:
OrderID | CustomerID | OrderDate |
10308 | 2 | 1996-09-18 |
10309 | 37 | 1996-09-19 |
10310 | 77 | 1996-09-20 |
Then, have a look at a selection from the "Customers" table:
CustomerID | CustomerName | ContactName | Country |
1 | Alfreds Futterkiste | Maria Anders | Germany |
2 | Ana Trujillo Emparedados y helados | Ana Trujillo | Mexico |
3 | Antonio Moreno Taquería | Antonio Moreno | Mexico |
Notice that the "CustomerID" column in the "Orders" table refers to the "CustomerID" in the "Customers" table. The relationship between the two tables above is the "CustomerID" column.
Then, if we run the following SQL statement (that contains an INNER JOIN):
Example
SELECT Orders.OrderID, Customers.CustomerName, Orders.OrderDate
FROM Orders
INNER JOIN Customers
ON Orders.CustomerID=Customers.CustomerID;
Try it Yourself »
it will produce something like this:
OrderID | CustomerName | OrderDate |
10308 | Ana Trujillo Emparedados y helados | 9/18/1996 |
10365 | Antonio Moreno Taquería | 11/27/1996 |
10383 | Around the Horn | 12/16/1996 |
10355 | Around the Horn | 11/15/1996 |
10278 | Berglunds snabbköp | 8/12/1996 |
Different SQL JOINs
Before we continue with examples, we will list the types of the different SQL JOINs you can use:
- INNER JOIN: Returns all rows when there is at least one match in BOTH tables
- LEFT JOIN: Return all rows from the left table, and the matched rows from the right table
- RIGHT JOIN: Return all rows from the right table, and the matched rows from the left table
- FULL JOIN: Return all rows when there is a match in ONE of the tables
SQL INNER JOIN Keyword
SQL INNER JOIN Keyword
The INNER JOIN keyword selects all rows from both tables as long as there is a match between the columns in both tables.
SQL INNER JOIN Syntax
SELECT column_name(s)
FROM table1
INNER JOIN table2
ON table1.column_name=table2.column_name;
or:
SELECT column_name(s)
FROM table1
JOIN table2
ON table1.column_name=table2.column_name;
PS! INNER JOIN is the same as JOIN.
Demo Database
In this tutorial we will use the well-known Northwind sample database.
Below is a selection from the "Customers" table:
CustomerID | CustomerName | ContactName | Address | City | PostalCode | Country |
1 | Alfreds Futterkiste | Maria Anders | Obere Str. 57 | Berlin | 12209 | Germany |
2 | Ana Trujillo Emparedados y helados | Ana Trujillo | Avda. de la Constitución 2222 | México D.F. | 05021 | Mexico |
3 | Antonio Moreno Taquería | Antonio Moreno | Mataderos 2312 | México D.F. | 05023 | Mexico |
And a selection from the "Orders" table:
OrderID | CustomerID | EmployeeID | OrderDate | ShipperID |
10308 | 2 | 7 | 1996-09-18 | 3 |
10309 | 37 | 3 | 1996-09-19 | 1 |
10310 | 77 | 8 | 1996-09-20 | 2 |
SQL INNER JOIN Example
The following SQL statement will return all customers with orders:
Example
SELECT Customers.CustomerName, Orders.OrderID
FROM Customers
INNER JOIN Orders
ON Customers.CustomerID=Orders.CustomerID
ORDER BY Customers.CustomerName;
Try it Yourself »
Note: The INNER JOIN keyword selects all rows from both tables as long as there is a match between the columns. If there are rows in the "Customers" table that do not have matches in "Orders", these customers will NOT be listed.
SQL LEFT JOIN Keyword
SQL LEFT JOIN Keyword
The LEFT JOIN keyword returns all rows from the left table (table1), with the matching rows in the right table (table2). The result is NULL in the right side when there is no match.
SQL LEFT JOIN Syntax
SELECT column_name(s)
FROM table1
LEFT JOIN table2
ON table1.column_name=table2.column_name;
or:
SELECT column_name(s)
FROM table1
LEFT OUTER JOIN table2
ON table1.column_name=table2.column_name;
PS! In some databases LEFT JOIN is called LEFT OUTER JOIN.
Demo Database
In this tutorial we will use the well-known Northwind sample database.
Below is a selection from the "Customers" table:
CustomerID | CustomerName | ContactName | Address | City | PostalCode | Country |
1 | Alfreds Futterkiste | Maria Anders | Obere Str. 57 | Berlin | 12209 | Germany |
2 | Ana Trujillo Emparedados y helados | Ana Trujillo | Avda. de la Constitución 2222 | México D.F. | 05021 | Mexico |
3 | Antonio Moreno Taquería | Antonio Moreno | Mataderos 2312 | México D.F. | 05023 | Mexico |
And a selection from the "Orders" table:
OrderID | CustomerID | EmployeeID | OrderDate | ShipperID |
10308 | 2 | 7 | 1996-09-18 | 3 |
10309 | 37 | 3 | 1996-09-19 | 1 |
10310 | 77 | 8 | 1996-09-20 | 2 |
SQL LEFT JOIN Example
The following SQL statement will return all customers, and any orders they might have:
Example
SELECT Customers.CustomerName, Orders.OrderID
FROM Customers
LEFT JOIN Orders
ON Customers.CustomerID=Orders.CustomerID
ORDER BY Customers.CustomerName;
Try it Yourself »
Note: The LEFT JOIN keyword returns all the rows from the left table (Customers), even if there are no matches in the right table (Orders).
SQL RIGHT JOIN Keyword
SQL RIGHT JOIN Keyword
The RIGHT JOIN keyword returns all rows from the right table (table2), with the matching rows in the left table (table1). The result is NULL in the left side when there is no match.
SQL RIGHT JOIN Syntax
SELECT column_name(s)
FROM table1
RIGHT JOIN table2
ON table1.column_name=table2.column_name;
or:
SELECT column_name(s)
FROM table1
RIGHT OUTER JOIN table2
ON table1.column_name=table2.column_name;
PS! In some databases RIGHT JOIN is called RIGHT OUTER JOIN.
Demo Database
In this tutorial we will use the well-known Northwind sample database.
Below is a selection from the "Orders" table:
OrderID | CustomerID | EmployeeID | OrderDate | ShipperID |
10308 | 2 | 7 | 1996-09-18 | 3 |
10309 | 37 | 3 | 1996-09-19 | 1 |
10310 | 77 | 8 | 1996-09-20 | 2 |
And a selection from the "Employees" table:
EmployeeID | LastName | FirstName | BirthDate | Photo | Notes |
1 | Davolio | Nancy | 12/8/1968 | EmpID1.pic | Education includes a BA in psychology..... |
2 | Fuller | Andrew | 2/19/1952 | EmpID2.pic | Andrew received his BTS commercial and.... |
3 | Leverling | Janet | 8/30/1963 | EmpID3.pic | Janet has a BS degree in chemistry.... |
SQL RIGHT JOIN Example
The following SQL statement will return all employees, and any orders they have placed:
Example
SELECT Orders.OrderID, Employees.FirstName
FROM Orders
RIGHT JOIN Employees
ON Orders.EmployeeID=Employees.EmployeeID
ORDER BY Orders.OrderID;
Try it Yourself »
Note: The RIGHT JOIN keyword returns all the rows from the right table (Employees), even if there are no matches in the left table (Orders).
SQL FULL OUTER JOIN Keyword
â?® Previous
SQL FULL OUTER JOIN Keyword
The FULL OUTER JOIN keyword returns all rows from the left table (table1) and from the right table (table2).
The FULL OUTER JOIN keyword combines the result of both LEFT and RIGHT joins.
SQL FULL OUTER JOIN Syntax
SELECT column_name(s)
FROM table1
FULL OUTER JOIN table2
ON table1.column_name=table2.column_name;
Demo Database
In this tutorial we will use the well-known Northwind sample database.
Below is a selection from the "Customers" table:
CustomerID | CustomerName | ContactName | Address | City | PostalCode | Country |
1 | Alfreds Futterkiste | Maria Anders | Obere Str. 57 | Berlin | 12209 | Germany |
2 | Ana Trujillo Emparedados y helados | Ana Trujillo | Avda. de la Constitución 2222 | México D.F. | 05021 | Mexico |
3 | Antonio Moreno Taquería | Antonio Moreno | Mataderos 2312 | México D.F. | 05023< 0 Like 0 Dislike Follow 0 Other Lessons for You How To Insert The Result Sets Of A Stored Procedure/Functions Into A Temporary Table In SQL Server? How to Insert the Result sets of a Stored Procedure/Functions into a Temporary Table in SQL Server In some cases with SQL Server, there may be an instance where you wish to take the resulting data from... Essential SQL Tips For Developers And For MS SQL DBA 10 Essential SQL Tips for Developers: SQL is yet another essential language for developers wishing to create data-driven websites. However, many developers are unfamiliar with various aspects of SQL;... Understanding Indexes In SQL Server Indexes in SQL Server are created on columns in tables or views. The index provides a faster way to look up data based on the values in those columns.For example, if you create an index on the primary... 10 Study Tips to Achieve your Goals This is particularly true of students that are looking to make the most of their study time and get better grades at Organization. 1. Set Study Goals: There is lots of credible research suggesting that... Rename The Logical Name Of SQL Server Database Files Using T-SQL Rename the logical name of SQL Server database files using T-SQL: 1. Problem: SQL Server database files have two names: one is the logical file name and the other is the physical file name. The logical... Find MS SQL Development Training near you
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