<-- Chapter 24: SQL Aliases
Chapter 25
SQL Joins
SQL Joins clause are used to combine data rows from two or more than two tables according to common field values between them.
Lets see an examples from the below tables "customers" :-
| customer_id |
name |
country |
| 1 |
abc |
India |
| 2 |
def |
Australia |
| 3 |
ghi |
USA |
| 4 |
jkl |
India |
| 5 |
mno |
Bangladesh |
Lets see an examples from the below tables "orders" :-
|
date
|
customer_id
|
amount
|
| 30-11-2015 |
2 |
3000 |
| 30-11-2015 |
1 |
1500 |
| 31-12-2015 |
1 |
2000 |
| 31-12-2015 |
3 |
2000 |
SQL JOIN syntax :-
SELECT `customers`.`name` AS [Customer Name], `orders`.`date` AS `Date`
FROM `orders`
JOIN `customers`
ON `orders`.`customer_id` = `customers`.`customer_id`;
Now run the above SQL query, we will see the output below :-
| Customer Name |
Date |
| def |
30-11-2015 |
| abc |
30-11-2015 |
| abc |
31-12-2015 |
| ghi |
31-12-2015 |
Now we can see here, we have displayed customer name and order date of customer on the basis of common customer_id between customers and orders tables.
There are different SQL Joins :-
- INNER JOIN
- LEFT JOIN
- RIGHT JOIN
- FULL JOIN
We will learn about all these JOINS in coming chapters.
Chapter 26: SQL Inner Join -->
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