码农教程 - 一技在手,衣食无忧! tools

目录

MySQL INNER JOIN Keyword

❮ Previous Next ❯

MySQL INNER JOIN Keyword

The INNER JOIN keyword selects records that have matching values in both tables.

MySQL INNER JOIN

INNER JOIN Syntax

SELECT column_name(s)
FROM table1
INNER 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 "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 "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

MySQL INNER JOIN Example

The following SQL statement selects all orders with customer information:

Example

SELECT Orders.OrderID, Customers.CustomerName
FROM Orders
INNER JOIN Customers ON Orders.CustomerID = Customers.CustomerID;
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 records in the "Orders" table that do not have matches in "Customers", these orders will not be shown!

JOIN Three Tables

The following SQL statement selects all orders with customer and shipper information:

Example

SELECT Orders.OrderID, Customers.CustomerName, Shippers.ShipperName
FROM ((Orders
INNER JOIN Customers ON Orders.CustomerID = Customers.CustomerID)
INNER JOIN Shippers ON Orders.ShipperID = Shippers.ShipperID);
Try it Yourself »

Test Yourself With Exercises

Exercise:

Choose the correct JOIN clause to select all records from the two tables where there is a match in both tables.

SELECT *
FROM Orders

ON Orders.CustomerID=
Customers.CustomerID;

Start the Exercise


❮ Previous Next ❯