sql

SQL

Tables

Users

Field	Type	Description
user_id	int	Primary Key and Unique identifier of the user
first_name	varchar	user First Name
last_name	varchar	User Last Name

Orders

Field	Type	Description
order_id	int	Primary Key and Unique identifier of the order
order_name	varchar	Order name
user_id	varchar	User who submitted order

Diagram

Task

Talk through each of the following SQL statements and what the problem with each is.

Problem 1

 SELECT user_id, last_name, first_name, FROM public.users;

Problem 2

SELECT * FROM public.users LEFT JOIN public.orders ON user_id = user_id;

Problem 3

SELECT count(user_id) AS "Count per last_name", last_name 
FROM public.users;

Problem 4

SELECT * FROM public.users WHERE first_name = "test";