Repairing buggy query server-side – without changes in the app More external apps are accessing our ERP SW database. As we were adding some columns into our structure, some queries from the external app become buggy because they are not specifying the targeted table in the query and errors out with Ambiguous column name… message.
The app vendor is inaccesible. We cannot repair the query from the app point nor change our structure (it’s for more customers).
Can we do something at the database server level?
You are facing the error Ambiguous column name… because the app is quering your database this way:
SELECT 
[Name], 
[Salary], 
[Name], 
[Age]
FROM TABLE1 A 
INNER JOIN TABLE2 B 
ON A.EmployeeID = B.EmployeeID

As you can see there are two [Name] in the SELECT. You will resolve the issue by recreating the query this way:
SELECT 
A.[Name], 
[Salary], 
B.[Name], 
[Age]
FROM TABLE1 A 
INNER JOIN TABLE2 B 
ON A.EmployeeID = B.EmployeeID

Yes, you are facing this because, as you said, you are adding some columns in your DB. You have 2 choices:

Contact the vendor and make it aware of the Ambiguous column name… error
Recreate the structure of your database and avoid using column names that were already used.