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关系型数据库 Postgresql 6.5.2

  Description:
    This method returns the current default database name specification, or 
    None if the environment variables should be used. Environment variables 
    won't be looked up.

  Syntax: set_defbase(base)
  Parameters:
    base          - new default base name (string/None)
  Return type:
    string, None  - previous default database name specification
  Exceptions raised:
    TypeError     - bad argument type, or too many arguments
  Description:
    This method sets the default database name value for new connections. If 
    None is supplied as parameter, environment variables will be used in 
    future connections. It returns the previous setting for default host.

  2.1.7. Module constants
  -----------------------

  Some constants are defined in the module dictionary. They are intended to be
used as parameters for methods calls. You should refer to PostgreSQL user 
manual for more information about them. These constants are:

  - large objects access modes, used by (pgobject.)locreate and 
    (pglarge.)open: (pg.)INV_READ, (pg.)INV_WRITE, (pg.)INV_ARCHIVE
  - positional flags, used by (pglarge.)seek: (pg.)SEEK_SET, 
    (pg.)SEEK_CUR, (pg.)SEEK_END.
  - version and __version__ constants that give the current version.

  2.1.9. 
  2.1.10. Miscellaneous attributes

  The following methods return information about the current connection.

  - 
2.2. pgobject description
---------------------------

  This object handle a connection to a PostgreSQL database. It embeds and 
hides all the parameters that define this connection, thus just leaving really
significant parameters in function calls.
  Some methods give direct access to the connection socket. They are specified
by the tag [DA]. DO NOT USE THEM UNLESS YOU REALLY KNOW WHAT YOU ARE DOING. If
you prefer disabling them, set the -DNO_DIRECT option in the Python Setup file.
  Some other methods give access to large objects (refer to PostgreSQL user
manual for more information about these). if you want to forbid access to these
from the module, set the -DNO_LARGE option in the Python Setup file. These 
methods are specified by the tag [LO].

  2.2.1. query - executes a SQL command string
  --------------------------------------------

  Syntax: query(command)
  Parameters:
    command       - SQL command (string)
  Return type:
    pgqueryobject, None    - result values
  Exceptions raised:
    TypeError     - bad argument type, or too many arguments.
    ValueError    - empty SQL query
    pg.error      - error during query processing, or invalid connection
  Description:
    This method simply sends a SQL query to the database. If the query is
    an insert statement, the return value is the OID of the newly
    inserted row.  If it is otherwise a query that does not return a result
    (ie. is not a some kind of SELECT statement), it returns None.
    Otherwise, it returns a pgqueryobject that can be accessed via the
    getresult method or printed.

  pgqueryobject methods
  ---------------------

    2.2.1.1. getresult - gets the values returned by the query
    -------------------------------------------------------------

    Syntax: getresult()
    Parameters: none
    Return type:
      list          - result values
    Exceptions raised:
      SyntaxError   - too many parameters
      pg.error      - invalid previous result
    Description:
      This method returns the list of the values returned by the query.
      More information about this result may be get using listfields,
      fieldname and fiednum methods.

    2.2.1.2. dictresult - like getresult but returns list of dictionaries
    ---------------------------------------------------------------------

    Syntax: dictresult()
    Parameters: none
    Return type:
      list          - result values as a dictionary
    Exceptions raised:
      SyntaxError   - too many parameters
      pg.error      - invalid previous result
    Description:
      This method returns the list of the values returned by the query
      with each tuple returned as a dictionary with the field names
      used as the dictionary index.


    2.2.1.3. listfields - lists the fields names of the previous query result
    -----------------------------------------------------------------------

    Syntax: listfields()
    Parameters: none
    Return type:
      list          - fields names
    Exceptions raised:
      SyntaxError   - too many parameters
      pg.error      - invalid previous result, or invalid connection
    Description:
      This method returns the list of names of the fields defined for the
      query result. The fields are in the same order as the result values.
  
    2.2.1.4. fieldname, fieldnum - field name-number conversion
    ---------------------------------------------------------

    Syntax: fieldname(i)
    Parameters:
      i              - field number (integer)
    Return type:
      string         - field name
    Exceptions raised:
      TypeError      - bad parameter type, or too many parameters
      ValueError     - invalid field number
      pg.error       - invalid previous result, or invalid connection
    Description:
      This method allows to find a field name from its rank number. It can be 
      useful for displaying a result. The fields are in the same order than the
      result values.

    Syntax: fieldnum(name)
    Parameters:
      name           - field name (string)
    Return type:
      integer        - field number
    Exceptions raised:
      TypeError      - bad parameter type, or too many parameters
      ValueError     - unknown field name
      pg.error       - invalid previous result, or invalid connection
    Description:
      This method returns a field number from its name.  It can be used to
      build a function that converts result list strings to their correct
      type, using a hardcoded table definition.  The number returned is the
      field rank in the result values list.

    2.2.1.5 ntuples - return number of tuples in query object
    ---------------------------------------------------------

    Syntax: ntuples()
    Parameters: None
    Return type: integer
    Description:
      This method returns the number of tuples found in a query.


  2.2.2. reset - resets the connection
  ------------------------------------

  Syntax: reset()
  Parameters: None
  Return type: None
  Exceptions raised:
    TypeError     -  too many (any) arguments
  Description:
    This method resets the current database.


  2.2.3. close - close the database connection
  --------------------------------------------

  Syntax: close()
  Parameters: none
  Return type: None
  Exceptions raised:
    TypeError     -  too many (any) arguments
  Description:
    This method closes the database connection.  The connection will
    be closed in any case when the connection is deleted but this
    allows you to explicitly close it.  It is mainly here to allow
    the DB-SIG API wrapper to implement a close function.


  2.2.4. fileno - returns the socket used to connect to the database
  ------------------------------------------------------------------

  Syntax: fileno()
  Parameters: none
    Exceptions raised:
    TypeError     -  too many (any) arguments
  Description:
    This method returns the underlying socket id used to connect
    to the database.  This is useful for use in select calls, etc.
    Note:  This function depends on having a recent version of the
    database.  See "-DNO_PQSOCKET" described above.


  2.2.5. getnotify - gets the last notify from the server
  -------------------------------------------------------

  Syntax: getnotify()
  Parameters: none
  Return type:
    tuple, None    - last notify from server
  Exceptions raised:
    SyntaxError    - too many parameters
    pg.error       - invalid connection
  Description:
    This methods try to get a notify from the server (from the SQL statement 
    NOTIFY). If the server returns no notify, the methods returns None. 
    Otherwise, it returns a tuple (couple) (relname, pid), where relname is the
    name of the notify and pid the process id of the connection that triggered 
    the notify.  Remember to do a listen query first otherwise getnotify
    will always return None.

  2.2.6. inserttable - insert a list into a table
  -----------------------------------------------

  Syntax: inserttable(table, values)
  Parameters:
    table          - the table name (string)
    values         - list of rows values (list)
  Return type:
    None
  Exception raised:
    pg.error       - invalid connection
    TypeError      - bad argument type, or too many arguments
  Description:
    This method allow to quickly insert large blocks of data in a table: it
    inserts the whole values list into the given table. The list is a list of
    tuples/lists that define the values for each inserted row. The rows values
    may contain string, integer, long or double (real) values. 
    BE VERY CAREFUL: this method doesn't typecheck the fields according to the
    table definition; it just look whether or not it knows how to handle such
    types.

  2.2.7. putline - writes a line to the server socket [DA]
  --------------------------------------------------------

  Syntax: putline(line)
  Parameters:
    line           - line to be written (string)
  Return type:
    None
  Exceptions raised:
    pg.error       - invalid connection
    TypeError      - bad parameter type, or too many parameters
  Description: 
    This method allows to directly write a string to the server socket.

  2.2.8. getline - gets a line from server socket [DA]
  ----------------------------------------------------

  Syntax: getline()
  Parameters: none
  Return type:
    string         - the line read
  Exceptions raised:
    pg.error       - invalid connection
    SyntaxError    - too many parameters
  Description:
    This method allows to directly read a string from the server socket.

  2.2.9. endcopy - synchronizes client and server [DA]
  ----------------------------------------------------

  Syntax: endcopy()
  Parameters: none
  Return type:
    None
  Exceptions raised:
    pg.error       - invalid connection
    SyntaxError    - too many parameters
  Description:
    The use of direct access methods may desynchonize client and server. This
    method ensure that client and server will be synchronized.

  2.2.10. locreate - creates of large object in the database [LO]
  ---------------------------------------------------------------

  Syntax: locreate(mode)
  Parameters:
    mode           - large object create mode
  Return type:
    pglarge        - object handling the postgres large object
  Exceptions raised:
    pg.error       - invalid connection, or creation error
    TypeError      - bad parameter type, or too many parameters
  Description:
    This method creates a large object in the database. The mode can be defined
    by OR-ing the constants defined in the pg module (INV_READ, INV_WRITE and
    INV_ARCHIVE). Please refer to PostgreSQL user manual for a description of
    the mode values.

  2.2.11. getlo - builds a large object from given oid [LO]
  ---------------------------------------------------------

  Syntax: getlo(oid)
  Parameters:
    oid            - oid of the existing large object (integer)
  Return type:
    pglarge        - object handling the postgres large object
  Exceptions raised:
    pg.error       - invalid connection
    TypeError      - bad parameter type, or too many parameters
    ValueError     - bad oid value (0 is invalid_oid)
  Description:
    This method allows to reuse a formerly created large object through the 
    pglarge interface, providing the user have its oid.

  2.2.12. loimport - import a file to a postgres large object [LO]
  ----------------------------------------------------------------

  Syntax: loimport(name)
  Parameters:
    name           - the name of the file to be imported (string)
  Return type:
    pglarge        - object handling the postgres large object
  Exceptions raised:
    pg.error       - invalid connection, or error during file import
    TypeError      - bad argument type, or too many arguments
  Description: 
    This methods allows to create large objects in a very simple way. You just 
    give the name of a file containing the data to be use.