question

I think these queries are basic and something you should learn by yourself to get the understanding of t-sql language, but today I am kind and give you the answers anyway.

I can't find order number or the customer number, but i think you mean order_id and customer_id

Question 1

select o.Order_Date, o.Order_Id, o.Customer_Id, p.Product_Id, p.Product_Description, ol.Ordered_Quantity 
from order_tx o
    inner join ORDER_LINE_TX ol
    	on o.Order_Id = ol.Order_Id
    inner join PRODUCT_TX p 
    	on ol.Product_Id = p.Product_Id
WHERE o.Order_id=1

Question 2 I do not understand what you mean by "cose", so you have to solve it by yourself.

Question 3

SELECT c.* FROM CUSTOMER_TX c
    LEFT JOIN ORDER_TX o
    	ON c.Customer_Id=o.Customer_Id
WHERE o.Order_Id IS NULL

Question 4

SELECT p.Product_Description, COUNT(Order_Id) FROM PRODUCT_TX p
    LEFT JOIN ORDER_LINE_TX ol
    	ON p.Product_Id=ol.Product_Id
GROUP BY p.Product_Description

Question 5

SELECT sv.Employee_Name, COUNT(e.Employee_ID) AS HeadCount FROM EMPLOYEE_TX as e
    INNER JOIN EMPLOYEE_TX AS sv
    	ON e.Employee_Supervisor=sv.Employee_Id
GROUP BY sv.Employee_Name
HAVING COUNT(e.Employee_ID)>1

Qustion 6

SELECT sv.Employee_Name 
FROM EMPLOYEE_TX as e
    INNER JOIN EMPLOYEE_TX AS sv
    	ON e.Employee_Supervisor=sv.Employee_Id
    INNER JOIN EMPLOYEE_SKILLS_TX s
    	ON e.Employee_Id=s.Employee_Id
WHERE s.Skill_Id='BS12'
GROUP BY
    sv.Employee_Name

Question 7 (this code work for SQL 2005)

SELECT  c.Customer_Id
FROM order_tx o
    INNER JOIN CUSTOMER_TX c 
    	ON o.Customer_Id=c.Customer_Id
    INNER JOIN (
    		SELECT Order_Id 
    		FROM ORDER_LINE_TX ol
    		WHERE ol.Product_Id =4
    		INTERSECT		
    		SELECT Order_Id 
    		FROM ORDER_LINE_TX ol
    		WHERE ol.Product_Id =3
    	) AS ol
    	ON o.Order_Id = ol.Order_Id