schema name in SQL statement.

["Masis, Alexander \(US SSA\)" <alexander.masis@xxxxxxxxxxxxxx>]

I have to explicitly specify the schema name to make SQL statement to
work.
Can I set the schema before the query, or set a default schema?
My current statement:
"SELECT col FROM schema.table"
I like to be able to use generic SQL statement like:
"SELECT col FROM table"