Как я могу проверить, существует ли Представление в Базе данных?

This is the most portable, least intrusive way:

select
    count(*)
from
    INFORMATION_SCHEMA.VIEWS
where
    table_name = 'MyView'
    and table_schema = 'MySchema'

Edit: This does work on SQL Server, and it doesn't require you joining to sys.schemas to get the schema of the view. This is less important if everything is dbo, but if you're making good use of schemas, then you should keep that in mind.

Each RDBMS has their own little way of checking metadata like this, but information_schema is actually ANSI, and I think Oracle and apparently SQLite are the only ones that don't support it in some fashion.

if it's Oracle you would use the "all_views" table.

It really depends on your dbms.