The like
operator takes two strings. These strings have to have compatible collations, which is explained here.
In my opinion, things then get complicated. The following query returns an error saying that the collations are incompatible:
select *
from INFORMATION_SCHEMA.TABLES
where 'abc' COLLATE SQL_Latin1_General_CP1_CI_AS like 'ABC' COLLATE SQL_Latin1_General_CP1_CS_AS
On a random machine here, the default collation is SQL_Latin1_General_CP1_CI_AS
. The following query is successful, but returns no rows:
select *
from INFORMATION_SCHEMA.TABLES
where 'abc' like 'ABC' COLLATE SQL_Latin1_General_CP1_CS_AS
The values "abc" and "ABC" do not match in a case-sensitve world.
In other words, there is a difference between having no collation and using the default collation. When one side has no collation, then it is "assigned" an explicit collation from the other side.
(The results are the same when the explicit collation is on the left.)