SQL Query Interview Questions

[dimkr]

Total number of items purchased by each customer or number of orders (assuming one row = one order) by each customer?

Code: Select all

SELECT CustomerID, SUM(Quantity) 
FROM Orders 
GROUP BY CustomerID;

or

Code: Select all

SELECT CustomerID, COUNT(*) 
FROM Orders 
GROUP BY CustomerID;

[rockedge]

Query for duplicate records:

Code: Select all

SELECT 
    CustomerID, 
    COUNT(CustomerID)
FROM
    Orders
GROUP BY CustomerID
HAVING COUNT(CustomerID) > 1;

Screenshot(26).jpg (40.82 KiB) Viewed 692 times

[user1234]

@rockedge, I am sorry to get off topic, but which program is this that you are using for running SQL queries? I am interested as we've just been taught how to run SQL queries in OpenOffice Database, but I am unsure if that is the program one uses for SQL in real life.

Thanks!

Regards
user1234

[rockedge]

@user1234 I am using phpmyadmin to work with MySQL databases!