CONNECT --+
 +---------+
 +-+---------------------------------------+--+
   +-> TO ----> runtime-options (1) -------+  |
 +--------------------------------------------+
 +-+---------------------------------------+--+
   +-> AS -+---------------------------+---+  |
           +-> runtime-options (2) ----+      |
 +--------------------------------------------+
 ++------------------------------------------+-+
  ++-+-> CATALOG --> runtime-options (3) +-+-+ |
   | +-> SCHEMA ---> rumtime-options (4) + |   |
   +--------------- , <--------------------+   |
 +---------------------------------------------+
 +-+---------------------------------------+----> ;
   +-> NAMES runtime-options (5) ----------+

 runtime-options

 --+---> 'literal' --------------+-->
   +---> parameter --------------+
   +---> parameter-marker -------+

Additional information available:

More Informationconnect expression

 The CONNECT statement associates an SQL environment with a connection
 and specifies a connection name for the association.

 An SQL environment is one or more databases that can be attached or
 detached as a unit.  When you execute a procedure, the databases that
 you specify in DECLARE ALIAS or ATTACH statements are the SQL
 environment for that procedure.  You can use the CONNECT statement to
 add another database to the current SQL environment or to substitute
 a different group of databases for the default SQL environment.

 You can issue two different CONNECT statements that attach to the
 same database, but each attach is unique.  Each CONNECT statement
 creates its own implicit transaction.

 You can use the connection name to specify a global database context
 when writing SQL modules for concurrent access to one or more
 databases.  Once you have specified a connection name in a CONNECT
 statement, you can refer to that name in subsequent SET CONNECT
 statements.  You can use a SET CONNECT statement to specify a new
 environment for a procedure to run against without having to detach
 and recompile queries.

 connect-expression =

 ---+--> DEFAULT --------------------+->
    ++-> db-specification -------+---+
     +-------- , <---------------+
 db-specification =

 -+-> ALIAS alias ---------------------------+
  |       +----------------------------------+
  |       +-+-----------------------------+-----+->
  |         ++-> FILENAME -> file-spec -+-+     |
  |          +-> PATHNAME -> path-name -+       |
  +-> ATTACH attach-expression -----------------+

Additional information available:

More information

 The TO runtime-options specifies the database environment.  You can
 supply a parameter marker from dynamic SQL, a host language variable
 from a precompiled SQL program, a parameter from an SQL module
 langauge module, or a string literal.  The argument that you supply
 must be a character string that contains a connect expression that is
 interpreted at run time.

 The db-specification specifies one or more valid aliases.  An alias,
 which identifies a particular database, is valid only if that
 database is either declared in any of the modules in the current
 application or attached with the ATTACH statement.  You can issue an
 ATTACH statement as part of the db-specificaiton.