Creates a database environment and a connection, and specifies a
    connection name for that association.

    A connection specifies an association between the set of cursors,
    intermediate result tables, and procedures in all modules of an
    application and the database environment currently attached.

    A database environment is one or more databases that can be
    attached or detached as a unit. The connection name designates a
    particular connection and database environment. When you execute
    a procedure, it executes in the context of a connection.

    When you issue a CONNECT statement, SQL creates a new connection
    from all the procedures in your application and creates a
    new environment from all the databases named in the CONNECT
    statement. The new environment can include databases already
    attached in the default environment.

    There are two ways to attach a database to the default
    environment:

    o  Use an ATTACH statement to specify a database environment at
       run time. All the databases you specify with subsequent ATTACH
       statements become part of the default environment.

    o  Use a DECLARE ALIAS statement to specify a database
       environment at compile time in precompiled SQL and SQL module
       language. All the databases that you specify using DECLARE
       ALIAS statements also become part of the default environment.

    A CONNECT statement creates a new connection with a new set
    of attachments, and does an implicit SET CONNECT to that new
    connection. Although a CONNECT statement does not create a
    transaction, each connection has its own implicit transaction
    context. You can issue two different CONNECT statements that
    attach to the same database, but each attach is unique.

    Once you have specified a connection name in a CONNECT statement,
    you can refer to that connection name in subsequent SET CONNECT
    statements. You can use a SET CONNECT statement to specify a new
    connection for an application to run against without having to
    detach and recompile queries. See the SET_CONNECT statement for
    more information.

    The DISCONNECT statement detaches from databases, ends the
    transactions in the connections that you specify, and rolls back
    all the changes you made since those transactions began.