Shortening SQL syntax

Question

I came across this piece of code while learning about Joining Tables in SQL.

Original code:
SELECT customers.ID, customers.Name, orders.Name, orders.Amount
FROM customers, orders
WHERE customers.ID=orders.Customer_ID
ORDER BY customers.ID;

Why can't we just write as:
SELECT customers.ID, customers.Name, orders.Name, orders.Amount
WHERE customers.ID=orders.Customer_ID
ORDER BY customers.ID;

removing the 'FROM' part, because table names are specified in 'SELECT' part anyway? Wouldn't the code be shorter this way if SQL syntax allowed to do so?

Answer 1

I guess the designers did not think of that.

OTOH, I think you would same more typing by including the FROM statement and using its alias feature - the AS phrase.

SELECT C.ID, C.Name, O.Name, O.Amount
FROM customers AS C, orders AS O
WHERE C.ID=O.Customer_ID
ORDER BY C.ID

Answer 2

The FROM clause is necessary, because as you can see from Brian's example, a table alias (shorter identifier) can be used.

How the server knows which actual tables are involved when the FROM clause was missing while table aliases are there? how to know what 'C' and 'O' represent?

Answer 3

In that case FROM becomes optional same as AS