Can I use Synonyms Name with Dot?

Question

I want to try thing like this:
I have set default schema for user 'AAAUser' as 'AAA' and 'BBBUser' as 'BBB'
and
create synonyms called 'DB_1.AAA.table_1' which link to 'DB_AAA..table_1'
and 'DB_1.BBB.table_1' which link to 'DB_BBB..table_1'.
So if I use AAAUser login to DB_1 and execute SQL:
Select * from DB_1..table_1
since the default schema of AAAUser is AAA, so the table is changed from DB_1..table_1 to DB_1.AAA.table_1
and there is synonym called DB_1.AAA.table_1, so it will link to DB_AAA..table_1.
And the same, if i use BBBUser login to DB_1 and call DB_1..table_1, will finally reach DB_BBB..table_1.
However, so far, it doesn't really work! I faced 2 issues:
1. If there is a table with the same name called dbo.table_1 in DB_1, even the default schema is AAA, the sql will go DB_1.dbo.table_1 directly! (I have already proved that if there is no same table name, the default schema AAA is used!)
2. I have tested the synonym:
select * from DB_1.AAA.table_1;
It doesn't work! but if i run:
select * from [DB_1.AAA.table_1];
It works!!
Why it that? Does it mean that My design above will never work?
Thanks!
Cliff

Answer 1

I am not able to understand what you are trying to achieve, but I think the root of your confusion is captured here:
select * from DB_1.AAA.table_1;
It doesn't work! but if i run:
select * from [DB_1.AAA.table_1];
These two SELECT are very different. The first SELECT accesses the object table_1 in the schema AAA in database DB_1. If table_1 is a synonym that may lead you to a different table.
The second SELECT accesses the object DB_1.AAA.table_1 in your default schema in the current database. There is no connection the database DB_1 or the schema AAA in that database here. The dots are just characters in the object name just like the D, B, underscore
and so on.
And specifically, the first SELECT cannot lead you to the object in the second SELECT, unless table_1 is a synonym with the value [DB_1.AAA.table_1].
Erland Sommarskog, SQL Server MVP, [email protected]