Alias for Tables Example

[hk21]

The following SQL statement selects all the orders from the customer with CustomerID=4 (Around the Horn). We use the "Customers" and "Orders" tables, and give them the table aliases of "c" and "o" respectively (Here we use aliases to make the SQL shorter): 

 

What does this example mean: How is it giving only 2 order id's from order table when there are many rows with employee id=4 in the orders table

Example

SELECT o.OrderID, o.OrderDate, c.CustomerName
FROM Customers AS c, Orders AS o
WHERE c.CustomerName="Around the Horn" AND c.CustomerID=o.CustomerID;

Try it Yourself »

[Funce]

This SQL is filtering by CustomerName of Around the horn, equivalenting to a CustomerID of 4. This is not the same as an employeeID.

IF you look closely at the returned set, you'll find that the two records have an employeeID of 6 and 8 respectively.

CustomerID	CustomerName	ContactName	Address	City	PostalCode	Country	OrderID	EmployeeID	OrderDate	ShipperID
4	Around the Horn	Thomas Hardy	120 Hanover Sq.	London	WA1 1DP	UK	10355	6	1996-11-15	1
4	Around the Horn	Thomas Hardy	120 Hanover Sq.	London	WA1 1DP	UK	10383	8	1996-12-16	3

[Makwana Prahlad]

Hello, @hk21

Please try this query,To Alias for Tables :

select s.state_name,c.city_name,a.area_name from State as s,Area as a,City as c where a.city_id=c.city_id AND c.state_id=s.state_id;

We use the State,City and Area tables and give them the table aliases of s,c and a respectively.

I hope above query will be useful for you.

Thank you.

 

 

Edited February 18, 2020 by Makwana Prahlad