在mySQL上加入3个表

Good Day.

I know this question is already asked but I have a hard time implementing my problem.

I want to Join 3 tables. Here is how my tables look like:

Order_Header(Order_Header_ID{PK}, Order_Date, Order_Time, Order_Complete)
Order_Line(Order_Line_ID{PK}, Product_ID{FK}, Order_Header_ID{FK},Quantity)
Products(Product_ID{PK}, Description, Cost)

I Want to JOIN the three tables so that in one table it displays Order_Header_ID, Quantity and Description out of the three tables WHERE Order_Complete = 'YES'. I have the following SQL that displays all the information but do not join them.

SELECT
    Order_Header.Order_Header_ID,
    Products.Description,
    Order_Line.Quantity
FROM Order_Header, Products, Order_Line
WHERE Order_Complete = 'yes'

The idea is that it list a Order_Header_ID once with the corresponding Description and Quantity only once.

Thank you in advance

Your current query is missing join conditions. Also, it is preferable to use an explicit join syntax. Correcting for both of these things we can write the following query:

SELECT
    oh.Order_Header_ID,
    p.Description,
    ol.Quantity
FROM Order_Header oh
INNER JOIN Order_Line ol
    ON oh.Order_Header_ID = ol.Order_Header_ID
INNER JOIN Products p
    ON ol.Product_ID = p.Product_ID
WHERE
    oh.Order_Complete = 'yes'