数据库模块封装完毕

上一篇 / 下一篇 2006-08-03 17:00:18 / 天气: 晴朗 / 心情: 高兴 / 个人分类：程序设计

昨天晚上加上今天白天完成了图书管理系统数据库操作模块的封装。准备明天开始做GUI前端，先学先做，估计要1周。再次感叹Python果然强大。

以下是我写的数据库模块

import MySQLdb
class db:
#构造函数，其中连接了数据库
def __init__(self , host , user , passwd):
try:
print "Open the Database"
self.conn = MySQLdb.connect(host , user , passwd)
except MySQLdb.OperationalError ,error:
print "Error %d: %s" % (error[0] , error[1])
#关闭数据库
def db_close(self):
self.conn.close()
print "close the database"

#使用数据库
def db_use(self , name):
str = "use " + name
result = self.db_execute_SQL(str)
return result
#查询数据库
def db_select(self , name , *arg):
str = "SELECT * FROM " + name + self.__str_join__(" " , arg)
result = self.db_execute_SQL(str)
return result

#向数据库添加数据
def db_insert(self , name , *value ):
str = "INSERT INTO " + name + " VALUES (" + self.__str_join__("," , value) + ")"
result = self.db_execute_SQL(str)
return result

#删除数据库中的数据
def db_delete(self , name , ID ):
str = "DELETE FROM " + name + " WHERE id = " + ID
result = self.db_execute_SQL(str)
return result
#修改数据库中的记录
def db_update(self , name , id , *arg):
str = "UPDATE " + name + " SET " + self.__str_join__("," , arg) + " WHERE id = " + id
result = self.db_execute_SQL(str)
return result
#向数据库中添加表
def db_create_table(self , name , *arg):
str = "CREATE TABLE " + name + "(" + self.__str_join__("," , arg) + ")"
result = self.db_execute_SQL(str)
return result

#删除数据库中的表
def db_drop_table(self , name):
str = "DROP TABLE " + name
result = self.db_execute_SQL(str)
return result

#修改数据库中的表
def db_alter_table(self , name , type , arg):
TYPE = ("ADD" , "DROP" , "RENAME")
if type in TYPE:
str = "ALTER TABLE " + name + " " + type + " " + arg
result = self.db_execute_SQL(str)
else:
print "You have an error in your SQL syntax;"
return False
return result
#察看表的结构
def db_describe(self , name):
str = "DESCRIBE " + name
result = self.db_execute_SQL(str)
return result

#执行SQL
def db_execute_SQL(self , str):
cursor = self.conn.cursor()
try:
print str
cursor.execute(str)
self.conn.commit()
allRecords = cursor.fetchall()
except MySQLdb.ProgrammingError , error:
print "You have an error in your SQL syntax;"
return False
except MySQLdb.OperationalError , error:
print "Error %d: %s" % (error[0] , error[1])
return False
if allRecords == ():
return True
else:
return allRecords
#用于连接SQL命令
def __str_join__(self , symbol , arg):
s = " "
for i in arg:
if s != " ":
s += symbol
s += i
return s

#用于测试的模块
if __name__=='__main__':
con = db("localhost" , "root" , "xxxxxxxxxxx")
con.db_execute_SQL("CREATE DATABASE books")
con.db_use("books")
con.db_create_table("books" , "id int" , "Title CHAR(20)" , "Author CHAR(20)")
con.db_insert("books" , '3' , "'dd'" , '"LeYan"')
con.db_insert("books" , "4" , '"JanusLe"' , '"fff"')
print con.db_select("books")
con.db_delete("books" , "4")
print con.db_select("books")
con.db_update("books" , "3" , 'Author = "NoName"')
print con.db_select("books")
con.db_alter_table("books" , "ADD" , "tttt varchar(20)")
print con.db_describe("books")
con.db_alter_table("books" , "DROP" , "tttt")
print con.db_describe("books")
con.db_close()

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