Python USES PyGreSQL to manipulate the PostgreSQL database tutorial

2020-04-02 13:52:13
OfStack

PostgreSQL is a powerful open source relational database. This article USES python to implement common operations on the open source database PostgreSQL.

I. environmental information:

1. Operating system

RedHat Enterprise Linux 4
Windows XP SP2

2. Database:

PostgreSQL8.3

3. Development tools:

Eclipse+Pydev+python2.6+PyGreSQL(pg module)

4. Description:

A. The PostgreSQL database runs on RedHat Linux, and pgAdmin (the client that accesses the PostgreSQL server) is also installed on Windows.
B. PyGreSQL(pg) module download path and API manual: http://www.pygresql.org/
Click here to PyGreSQL module (link: http://xiazai.jb51.net/201407/tools/pygresql (jb51.net). Rar)

Ii. Configuration:

1. Add the following subdirectories under the pgAdmin installation path to the system environment variables:

E: \ \ Program Files \ PostgreSQL \ 8.3 \ lib

E: \ \ Program Files \ PostgreSQL \ 8.3 \ bin

2. Copy the DLL file from the python installation directory C:\ python 26\Lib\site-packages\pywin32_system32 to C:\WINDOWS\system32

3. Note: if you skip the above two steps, you will report an error when importing pg, and it will take a long time to complete.

Iii. Program implementation:


#!/usr/bin/env python
# -*- coding: utf-8 -*-

# Import log and pg The module 
import logging
import logging.config
import pg

# Log profile name 
LOG_FILENAME = 'logging.conf'

# Log statement prompt information 
LOG_CONTENT_NAME = 'pg_log'

def log_init(log_config_filename, logname):
  '''
  Function: Log module initialization function 
  Input : log_config_filename: Log profile name 
      lognmae: Prompt statement before each log 
  Output: logger
  author: socrates
  date:2012-02-12
  '''
  logging.config.fileConfig(log_config_filename)
  logger = logging.getLogger(logname)
  return logger

def operate_postgre_tbl_product():
  '''
  Function: operation pg Database function 
  Input : NONE
  Output: NONE
  author: socrates
  date:2012-02-12
  ''' 
  pgdb_logger.debug("operate_postgre_tbl_product enter...") 
  
  # Connect to database  
  try:
    pgdb_conn = pg.connect(dbname = 'kevin_test', host = '192.168.230.128', user = 'dyx1024', passwd = '888888')
  except Exception, e:
     print e.args[0]
     pgdb_logger.error("conntect postgre database failed, ret = %s" % e.args[0])  
     return  
   
  pgdb_logger.info("conntect postgre database(kevin_test) succ.") 
    
  # Delete table 
  sql_desc = "DROP TABLE IF EXISTS tbl_product3;"
  try:
    pgdb_conn.query(sql_desc)
  except Exception, e:
    print 'drop table failed'
    pgdb_logger.error("drop table failed, ret = %s" % e.args[0])
    pgdb_conn.close() 
    return
  
  pgdb_logger.info("drop table(tbl_product3) succ.") 
 
  # Create a table 
  sql_desc = '''CREATE TABLE tbl_product3(
    i_index INTEGER,
    sv_productname VARCHAR(32)
    );'''
  try:  
    pgdb_conn.query(sql_desc)
  except Exception, e:
    print 'create table failed'
    pgdb_logger.error("create table failed, ret = %s" % e.args[0])
    pgdb_conn.close() 
    return    
  
  pgdb_logger.info("create table(tbl_product3) succ.") 
   
  # Insert records   
  sql_desc = "INSERT INTO tbl_product3(sv_productname) values('apple')"
  try:
    pgdb_conn.query(sql_desc)
  except Exception, e:
    print 'insert record into table failed'
    pgdb_logger.error("insert record into table failed, ret = %s" % e.args[0])
    pgdb_conn.close() 
    return  
   
  pgdb_logger.info("insert record into table(tbl_product3) succ.")   
   
  # Lookup table  1    
  sql_desc = "select * from tbl_product3"
  for row in pgdb_conn.query(sql_desc).dictresult():
    print row
    pgdb_logger.info("%s", row) 
 
  # Lookup table 2    
  sql_desc = "select * from tbl_test_port"
  for row in pgdb_conn.query(sql_desc).dictresult():
    print row 
    pgdb_logger.info("%s", row)    
   
  # Close the database connection    
  pgdb_conn.close()    
  pgdb_logger.debug("operate_sqlite3_tbl_product leaving...") 

if __name__ == '__main__': 
  
  # Initialize the logging system 
  pgdb_logger = log_init(LOG_FILENAME, LOG_CONTENT_NAME)  
  
  # Operational database 
  operate_postgre_tbl_product()

Iv. Test

1. Printed results on the command line after operation:


{'sv_productname': 'apple', 'i_index': None}
{'i_status': 1, 'i_port': 2, 'i_index': 1}
{'i_status': 1, 'i_port': 3, 'i_index': 2}
{'i_status': 1, 'i_port': 5, 'i_index': 3}
{'i_status': 1, 'i_port': 0, 'i_index': 5}
{'i_status': 1, 'i_port': 18, 'i_index': 7}
{'i_status': 1, 'i_port': 8, 'i_index': 8}
{'i_status': 1, 'i_port': 7, 'i_index': 9}
{'i_status': 1, 'i_port': 21, 'i_index': 10}
{'i_status': 1, 'i_port': 23, 'i_index': 11}
{'i_status': 1, 'i_port': 29, 'i_index': 12}
{'i_status': 1, 'i_port': 3000, 'i_index': 4}
{'i_status': 1, 'i_port': 1999, 'i_index': 6}

2. Log file contents:


[2012-02-12 18:09:53,536 pg_log]DEBUG: operate_postgre_tbl_product enter... (test_func.py:36)
[2012-02-12 18:09:53,772 pg_log]INFO: conntect postgre database(kevin_test) succ. (test_func.py:46)
[2012-02-12 18:09:53,786 pg_log]INFO: drop table(tbl_product3) succ. (test_func.py:58)
[2012-02-12 18:09:53,802 pg_log]INFO: create table(tbl_product3) succ. (test_func.py:73)
[2012-02-12 18:09:53,802 pg_log]INFO: insert record into table(tbl_product3) succ. (test_func.py:85)
[2012-02-12 18:09:53,802 pg_log]INFO: {'sv_productname': 'apple', 'i_index': None} (test_func.py:91)
[2012-02-12 18:09:53,802 pg_log]INFO: {'i_status': 1, 'i_port': 2, 'i_index': 1} (test_func.py:97)
[2012-02-12 18:09:53,802 pg_log]INFO: {'i_status': 1, 'i_port': 3, 'i_index': 2} (test_func.py:97)
[2012-02-12 18:09:53,802 pg_log]INFO: {'i_status': 1, 'i_port': 5, 'i_index': 3} (test_func.py:97)
[2012-02-12 18:09:53,802 pg_log]INFO: {'i_status': 1, 'i_port': 0, 'i_index': 5} (test_func.py:97)
[2012-02-12 18:09:53,819 pg_log]INFO: {'i_status': 1, 'i_port': 18, 'i_index': 7} (test_func.py:97)
[2012-02-12 18:09:53,819 pg_log]INFO: {'i_status': 1, 'i_port': 8, 'i_index': 8} (test_func.py:97)
[2012-02-12 18:09:53,819 pg_log]INFO: {'i_status': 1, 'i_port': 7, 'i_index': 9} (test_func.py:97)
[2012-02-12 18:09:53,819 pg_log]INFO: {'i_status': 1, 'i_port': 21, 'i_index': 10} (test_func.py:97)
[2012-02-12 18:09:53,819 pg_log]INFO: {'i_status': 1, 'i_port': 23, 'i_index': 11} (test_func.py:97)
[2012-02-12 18:09:53,819 pg_log]INFO: {'i_status': 1, 'i_port': 29, 'i_index': 12} (test_func.py:97)
[2012-02-12 18:09:53,819 pg_log]INFO: {'i_status': 1, 'i_port': 3000, 'i_index': 4} (test_func.py:97)
[2012-02-12 18:09:53,819 pg_log]INFO: {'i_status': 1, 'i_port': 1999, 'i_index': 6} (test_func.py:97)
[2012-02-12 18:09:53,819 pg_log]DEBUG: operate_sqlite3_tbl_product leaving... (test_func.py:101)

3. PSQL results:


[root@kevin ~]# su - postgres
[postgres@kevin ~]$ psql -U dyx1024 -d kevin_test
psql (8.4.2)
Type "help" for help.

kevin_test=# dt
        List of relations
 Schema |   Name   | Type |   Owner   
--------+---------------+-------+----------------
 public | tbl_product3 | table | dyx1024
 public | tbl_test_port | table | pg_test_user_3
(2 rows)

kevin_test=# select * from tbl_product3;
 i_index | sv_productname 
---------+----------------
     | apple
(1 row)

kevin_test=# select * from tbl_test_port;
 i_index | i_port | i_status 
---------+--------+----------
    1 |   2 |    1
    2 |   3 |    1
    3 |   5 |    1
    5 |   0 |    1
    7 |   18 |    1
    8 |   8 |    1
    9 |   7 |    1
   10 |   21 |    1
   11 |   23 |    1
   12 |   29 |    1
    4 |  3000 |    1
    6 |  1999 |    1
(12 rows)

kevin_test=# q
[postgres@kevin ~]$