Inner Join Invalid Object Name - sql

Question

Trying to do a simple inner join query but keep getting errors
Select Alias from Db.SchmaName.Customers as Customer
Select Alias from Db.SchmaName.Orders as Order
Inner Join Order on Customer.Alias = Order.Alias
The Db and SchmaNames are both exactly the same but Alias column is different between the 2 tables.
Both of the select statements work as expected but the error for the Inner Join is
"Invalid object name 'Order'"
I get this error even if I do not use the table alias and instead type out the full path to the table

Answer 1

I'm surprised that's the error you're getting. ORDER is a reserved word in SQL Server, don't use it for your object and alias names, you should be getting the error:
Incorrect syntax near 'order'.
Don't use reserved words (or even key words really) for object names, or if you have to, quote them ([Order]). Personally I would do:
SELECT Alias --This is missing an alias as well, so would be ambigous
FROM Db.SchmaName.Orders O
INNER JOIN Customer C ON C.Alias = O.Alias;
Aliases are great for making your SQL succinct. Aliasing the table Customers as Customer, doesn't really do that. A lot of people (like myself), tend to use a few characters to alias a table. So, for Customer I used C. Personally, I tend to use the letters of specific words in the object's name. For example, if I have a table called StockItem I would probably use SI. For a table I have called ic_BD_HPT1 I use HPT1.

Answer 2

Those are two queries, not one.
Select Alias from Db.SchmaName.Customers as Customer
Select Alias from Db.SchmaName.Orders as Order
Inner Join Order on Customer.Alias = Order.Alias
Is actually
Select Alias from Db.SchmaName.Customers as Customer;
Select Alias from Db.SchmaName.Orders as Order
Inner Join Order on Customer.Alias = Order.Alias;
The second query is invalid, as it tries to join the Order alias to itself.
To join two tables you need to specify the tables themselves in the FROM, JOIN statements. If you want to select a column that exists in both tables you have to explicitly specify which one you want, eg:
Select Order.Alias
from Db.SchmaName.Orders as [Order]
Inner Join Db.SchmaName.Customers as Customer
on Customer.Alias = [Order].Alias;
ORDER is a keyword which means you need to either enclose it in square brackets or use a better alias. In fact, Orders is just fine :
Select Orders.Alias
from Db.SchmaName.Orders
Inner Join Db.SchmaName.Customers as Customer
on Customer.Alias = Orders.Alias;

Answer 3

use different table alias name rather key word of SQL(Order),another issue Alias column is exist in your both table so use table.column in selection and
your join need like below
Select Customer.Alias from Db.SchmaName.Customers as Customer
inner join Db.SchmaName.Orders as O
on Customer.Alias = O.Alias

Answer 4

Order is a Keyword in SQL. You can not use Keywords in SQL for aliases, except if you put [] around the alias.
I would use a different name for the alias.

Answer 5

There are two queries in your question.
This is one
Select Alias from Db.SchmaName.Customers as Customer
And this is the second one
Select Alias from Db.SchmaName.Orders as Order
Inner Join Order on Customer.Alias = Order.Alias
The error you are getting is on the second query,
You are trying to JOIN against the Alias you've given to the table Orders, i.e ORDER. What you should do instead is reference the Alias on the ON clause, like so
Select Order.Alias, Customer.Alias
from Db.SchmaName.Orders as Order
INNER JOIN Db.SchmaName.Customers as Customer on Order.Alias = Customer.Alias