Python操作db2

官方文檔：https://www.ibm.com/support/knowledgecenter/en/SSEPGG_9.5.0/com.ibm.db2.luw.apdv.python.doc/doc/t0054682.html

 

import ibm_db
conn = ibm_db.connect("database=MICRO_11; "
                           "hostname=localhost; "
                           "port=50000; "
                           "protocol=tcpip; "
                           "uid=administrator; "
                           "pwd=wyz", "", "")
stmt = ibm_db.exec_immediate(conn,"SELECT SYS_ORG_TYPE_CODE,SYS_ORG_TYPE_NAME "
                                  "FROM SYS_ORG_TYPE_TB "
                                  "WHERE SYS_ORG_TYPE_UPID IS NOT NULL")
# if結果集條數為0：result==False
# if結果集條數>0：結果為一個tuple
result = ibm_db.fetch_tuple(stmt)
while result:
    print(result[0], result[1]) # 順序和select字段順序一樣
    result = ibm_db.fetch_tuple(stmt)

 

一、建連接：

'''
ibm_db.connect() #非持久性連接
ibm_db.pconnect()  #持久性連接，提升性能，連接不關閉
'''
import ibm_db
conn = ibm_db.connect("dsn=name","username","password")
#連接cataloged或非cataloged數據庫
ibm_db.connect("DATABASE=name;HOSTNAME=host;PORT=60000;PROTOCOL=TCPIP;UID=username;
                PWD=password;", "", "")

二、執行SQL：

不帶參數的

'''
string可以為XQuery表達式，用XMLQuery包裝的
如果將用戶輸入作為SQL變量，可能受到SQL注入攻擊
返回的是cursor類型，調用 ibm_db.num_rows()可以得到影響的數據行數
如果執行錯誤，可通過ibm_db.stmt_error() 或 ibm_db.stmt_errormsg()得到錯誤信息
'''
import ibm_db
conn = ibm_db.connect("dsn=name","username","password")
stmt = ibm_db.exec_immediate(conn, "UPDATE employee SET bonus = '1000' WHERE job = 'MANAGER'")
print "Number of affected rows: ", ibm_db.num_rows(stmt)
# XQuery
if conn:
    sql = "SELECT XMLSERIALIZE(XMLQUERY('for $i in $t/address where $i/city = \"Olathe\" return <zip>{$i/zip/text()}</zip>' passing c.xmlcol as \"t\") AS CLOB(32k)) FROM xml_test c WHERE id = 1"
    stmt = ibm_db.exec_immediate(conn, sql)
    result = ibm_db.fetch_both(stmt)
    while( result ):
        print "Result from XMLSerialize and XMLQuery:", result[0]
        result = ibm_db.fetch_both(stmt)

 帶參數的：

'''
ibm_db.prepare(), ibm_db.bind_param()，ibm_db.execute()三個方法
准備語句可以提高性能，因為數據庫服務器為數據檢索創建了優化的訪問計划，如果再次執行該語句，則可以重用它
'''
import ibm_db
conn = ibm_db.connect("dsn=name","username","password")
sql = "SELECT EMPNO, LASTNAME FROM EMPLOYEE WHERE EMPNO > ? AND EMPNO < ?"
stmt = ibm_db.prepare(conn, sql)
max = 50
min = 0
# 綁定參數
ibm_db.bind_param(stmt, 1, min)
ibm_db.bind_param(stmt, 2, max)
ibm_db.execute(stmt)
# Process results

# Invoke prepared statement again using dynamically bound parameters
param = max, min, 
ibm_db.execute(stmt, param)

 三、檢索結果集：ibm_db.fetch_both(stmt,num) 如果指定游標為scrollable類型，【在調用ibm_db.exec_immediate()或ibm_db.prepare()的時候】，num為檢索的行數

import ibm_db
#  第一種方式：
conn = ibm_db.connect( "dsn=name", "username", "password" )
sql = "SELECT * FROM EMPLOYEE"
stmt = ibm_db.exec_immediate(conn, sql)
dictionary = ibm_db.fetch_both(stmt)
while dictionary != False:
    print "The ID is : ",  dictionary["EMPNO"]
    print "The Name is : ", dictionary[1]
    dictionary = ibm_db.fetch_both(stmt)
#  第二種方式：
tuple = ibm_db.fetch_tuple(stmt)
while tuple != False:
    print "The ID is : ", tuple[0]
    print "The name is : ", tuple[1]
    tuple = ibm_db.fetch_tuple(stmt)
# 第三種方式：
dictionary = ibm_db.fetch_assoc(stmt)
while dictionary != False:
    print "The ID is : ", dictionary["EMPNO"]
    print "The name is : ", dictionary["FIRSTNME"]
    dictionary = ibm_db.fetch_assoc(stmt)
# 第四種方式：
while ibm_db.fetch_row(stmt) != False:
    print "The Employee number is : ",  ibm_db.result(stmt, 0)
    print "The Name is : ", ibm_db.result(stmt, "NAME")

 四、調用存儲過程

import ibm_db

conn = ibm_db.connect("dsn=sample","username","password")
if conn:
      sql = 'CALL match_animal(?, ?, ?)'
      stmt = ibm_db.prepare(conn, sql)
    
      name = "Peaches"
      second_name = "Rickety Ride"
      weight = 0
      ibm_db.bind_param(stmt, 1, name, ibm_db.SQL_PARAM_INPUT)
      ibm_db.bind_param(stmt, 2, second_name, ibm_db.SQL_PARAM_INPUT_OUTPUT)
      ibm_db.bind_param(stmt, 3, weight, ibm_db.SQL_PARAM_OUTPUT)
    
      print "Values of bound parameters _before_ CALL:"
      print "  1: %s 2: %s 3: %d\n" % (name, second_name, weight)
    
      if ibm_db.execute(stmt):
        print "Values of bound parameters _after_ CALL:"
        print "  1: %s 2: %s 3: %d\n" % (name, second_name, weight)

五、開啟事務：適合大批量插入數據提升性能

import ibm_db

array = { ibm_db.SQL_ATTR_AUTOCOMMIT : ibm_db.SQL_AUTOCOMMIT_OFF }
conn = ibm_db.pconnect("dsn=SAMPLE", "user", "password", array)
sql = "DELETE FROM EMPLOYEE"
try:
   stmt = ibm_db.exec_immediate(conn, sql)
except:
   print "Transaction couldn't be completed."
   ibm_db.rollback(conn)
else:
   ibm_db.commit(conn)
   print "Transaction complete."

六、錯誤處理：

第一種：

import ibm_db 
try:
    conn = ibm_db.connect("dsn=sample","user","password")     
except:     
    print "no connection:", ibm_db.conn_errormsg()
else:
    print "The connection was successful" 

第二種：

import ibm_db
conn = ibm_db.connect( "dsn=sample", "user", "password")
sql = "DELETE FROM EMPLOYEE"
try:
   stmt = ibm_db.exec_immediate(conn, sql)
except:
   print "Transaction couldn't be completed:" , ibm_db.stmt_errormsg()
else:
   print "Transaction complete."

七、查看元數據

注意：調用元數據函數消耗大量的空間。如果可能的話，考慮緩存調用的結果以便在后續調用中使用。

ibm_db.client_info()	返回包含數據庫客戶端信息的只讀對象.
ibm_db.column_privileges()	返回一個結果集，列出表的column和其關聯特權
ibm_db.columns()	返回一個結果集，列出表的column和其關聯元數據
ibm_db.foreign_keys()	返回一個結果集，列出表的column和其關聯元數據
ibm_db.primary_keys()	返回一個結果集，列出表的外鍵
ibm_db.procedure_columns()	返回一個結果集，列出一個或多個存儲過程的參數
ibm_db.procedures()	返回一個結果集，列出數據庫里注冊了的的存儲過程
ibm_db.server_info()	返回包含數據庫服務器信息的只讀對象.
ibm_db.special_columns()	返回一個結果集，列出 表的唯一行標識符列
ibm_db.statistics()	返回一個結果集，列出表的索引和統計信息
ibm_db.table_privileges()	返回一個結果集，列出數據庫中的表和相關權限。

 

import ibm_db

conn = ibm_db.connect("dsn=sample", "user", "password")
client = ibm_db.client_info(conn)

# DB客戶端信息
if client:
    print "DRIVER_NAME: string(%d) \"%s\"" % (len(client.DRIVER_NAME), client.DRIVER_NAME)
    print "DRIVER_VER: string(%d) \"%s\"" % (len(client.DRIVER_VER), client.DRIVER_VER)
    print "DATA_SOURCE_NAME: string(%d) \"%s\"" % (len(client.DATA_SOURCE_NAME), client.DATA_SOURCE_NAME)
    print "DRIVER_ODBC_VER: string(%d) \"%s\"" % (len(client.DRIVER_ODBC_VER), client.DRIVER_ODBC_VER)
    print "ODBC_VER: string(%d) \"%s\"" % (len(client.ODBC_VER), client.ODBC_VER)
    print "ODBC_SQL_CONFORMANCE: string(%d) \"%s\"" % (len(client.ODBC_SQL_CONFORMANCE), client.ODBC_SQL_CONFORMANCE)
    print "APPL_CODEPAGE: int(%s)" % client.APPL_CODEPAGE
    print "CONN_CODEPAGE: int(%s)" % client.CONN_CODEPAGE
    ibm_db.close(conn)
else:
    print "Error."

# DB服務器信息
server = ibm_db.server_info(conn)

if server:
    print "DBMS_NAME: string(%d) \"%s\"" % (len(server.DBMS_NAME), server.DBMS_NAME)
    print "DBMS_VER: string(%d) \"%s\"" % (len(server.DBMS_VER), server.DBMS_VER)
    print "DB_NAME: string(%d) \"%s\"" % (len(server.DB_NAME), server.DB_NAME)
    ibm_db.close(conn)
else:
    print "Error."