PyGreSQL - Python Interface
Chapter 6. PyGreSQL - Python Interface
- Table of Contents
- 6.1. The pg Module
- 6.2. pg Module Functions
- connect -- open a connection to the database server
- get_defhost -- get default host name [DV]
- set_defhost -- set default host name [DV]
- get_defport -- get default port [DV]
- set_defport -- set default port [DV]
- get_defopt -- get default options specification [DV]
- set_defopt -- set default options specification [DV]
- get_deftty -- get default connection debug terminal specification [DV]
- set_deftty -- set default connection debug terminal specification [DV]
- get_defbase -- get default database name specification [DV]
- set_defbase -- set default database name specification [DV]
- 6.3. Connection Object:
pgobject - query -- execute a SQL command
- reset -- reset the connection
- close -- close the database connection
- fileno -- return the socket used to connect to the database
- getnotify -- get the last notify from the server
- inserttable -- insert a list into a table
- putline -- write a line to the server socket [DA]
- getline -- get a line from server socket [DA]
- endcopy -- synchronize client and server [DA]
- locreate -- create a large object in the database [LO]
- getlo -- build a large object from given OID [LO]
- loimport -- import a file to a PostgreSQL large object [LO]
- 6.4. Database Wrapper Class:
DB - pkey -- return the primary key of a table
- get_databases -- get list of databases in the system
- get_tables -- get list of tables in connected database
- get_attnames -- return the attribute names of a table
- get -- get a tuple from a database table
- insert -- insert a tuple into a database table
- update -- update a database table
- clear -- clear a database table
- delete -- delete a row from a table
- 6.5. Query Result Object:
pgqueryobject - getresult -- get the values returned by the query
- dictresult -- get the values returned by the query as a list of dictionaries
- listfields -- list the fields names of the query result
- fieldname -- get field name by number
- fieldnum -- get field number by name
- ntuples -- return the number of tuples in query object
- 6.6. Large Object:
pglarge - open -- open a large object
- close -- close the large object
- read -- read from the large object
- write -- write to the large object
- seek -- change current position in the large object
- tell -- return current position in the large object
- unlink -- delete the large object
- size -- return the large object size
- export -- save the large object to file
Author: Written by D'Arcy J.M. Cain (
<[email protected]>). Based heavily on code written by Pascal Andre<[email protected]>. Copyright © 1995, Pascal Andre. Further modifications Copyright © 1997-2000 by D'Arcy J.M. Cain.
You may either choose to use the old mature interface provided by the pg module or otherwise the newer pgdb interface compliant with the DB-API 2.0 specification developed by the Python DB-SIG.
Here we describe only the older pg API. As long as PyGreSQL does not contain a description of the DB-API you should read about the API at http://www.python.org/topics/database/DatabaseAPI-2.0.html.
A tutorial-like introduction to the DB-API can be found at http://www2.linuxjournal.com/lj-issues/issue49/2605.html
6.1. The pg Module
The pg module defines three objects:
pgobject, which handles the connection and all the requests to the database,pglargeobject, which handles all the accesses to PostgreSQL large objects, andpgqueryobjectthat handles query results.
If you want to see a simple example of the use of some of these functions, see http://www.druid.net/rides where you can find a link at the bottom to the actual Python code for the page.
6.1.1. Constants
Some constants are defined in the pg module dictionary. They are intended to be used as a parameters for methods calls. You should refer to the libpq description (Chapter 1) for more information about them. These constants are:
- INV_READ
INV_WRITE large objects access modes, used by
(pgobject.)locreateand(pglarge.)open.- SEEK_SET
SEEK_CUR
SEEK_END positional flags, used by
(pglarge.)seek.- version
__version__ constants that give the current version