column-name =

  ---+----------->-----------------+-> <name-of-column> -->
     +-> <table-name> -------+> . -+
     +-> <view-name> --------+
     +-> <correlation-name> -+

    You can name columns in CREATE TABLE and ALTER TABLE statements.
    In other SQL statements, the names you give to columns can be
    qualified by table name, view names, or aliases.

    The only time you must qualify column names is when they are
    ambiguous. Joining a table with itself and joining two tables
    with common column names are two cases that require qualified
    column names.

    You always have the option of qualifying column names. In complex
    statements, such qualifiers often make the statements more
    readable.