MYSQLDB Operational Database (iii)

Delete Data
Delete A single piece of data

#conding=utf-8import MySQLdbimport randomtry:    conn = MySQLdb.connect(        host = ‘127.0.0.1‘,        user = ‘root‘,        passwd = "123456",        port = 3306)    conn.select_db(‘python‘)# 选择pythonDB数据库    cur = conn.cursor()# 获取游标    cur.execute("delete from user where id=0")    cur.execute("select * from user")    for v in cur.fetchall():        print v    cur.close()    conn.commit()    conn.close()    print u"sql执行成功"except Exception, e:print e

Delete more than one piece of data

#conding=utf-8import MySQLdbimport randomtry:    conn = MySQLdb.connect(        host = ‘127.0.0.1‘,        user = ‘root‘,        passwd = "123456",        port = 3306)    conn.select_db(‘python‘)# 选择pythonDB数据库    cur = conn.cursor()# 获取游标    sql = "delete from user where id=%s"    cur.executemany(sql,[(3),(2,)])    cur.execute("select * from user")    for v in cur.fetchall():        print v    cur.close()    conn.commit()    conn.close()    print u"sql执行成功"except Exception, e:    print e

Transaction rollback

import MySQLdbimport randomtry:    conn = MySQLdb.connect(        host = ‘127.0.0.1‘,        user = ‘root‘,        passwd = "123456",        port = 3306)    conn.select_db(‘python‘)#     cur = conn.cursor()# 获取游标    cur.execute("select * from user")    datas = cur.fetchall()    print u"修改前的数据：\n", datas[0]    cur.execute("update user set birthday=‘2100-08-12‘where name=‘tom6")    cur.execute("select * from user")    datas = cur.fetchall()    print u"修改后的数据：\n", datas[0]    #回滚事务    conn.rollback()    cur.execute("select * from user")    datas = cur.fetchall()    print u"事务回滚后的数据：\n", datas[0]    #关闭游标    cur.close()    #提交事务    conn.commit()    #关闭数据库连接    conn.close()    print u"sql语句执行成功！"except Exception, e:    print e

Reset Cursor Position
Scroll (value, mode= ' relative ')
Moves the pointer to the line specified by the parameter value;
Mode = relative indicates that the value row is moved forward from the current row
The Mode=absolute represents the value row that is moved to the absolute position. Cursor Index starting from 0
Cursor.rownumber
Returns the position of the current cursor

database table Contents:

  #coding =utf-8import mysqldb# Open the database connection conn = MySQLdb.connect (host = "localhost", port = 3306, user = "R Oot ", passwd =" 123456 ", db =" Python ", CharSet =" UTF8 ") #使用cursor () method gets the operation cursors of the database cursor = conn.cursor () cursor. Execute ("SELECT * from the user order by id") Print u "Current cursor location:", Cursor.rownumberprint cursor.fetchone () print U "Current cursor location:", C Ursor.rownumbercursor.scroll (0,mode= "Absolute") #移动游标到第一行print U "Current cursor location:", Cursor.rownumberprint Cursor.fetchone ()

#coding=utf-8import MySQLdb#打开数据库连接conn = MySQLdb.connect(    host = "localhost",     port = 3306,    user = "root",     passwd = "123456",     db = "python",     charset = "utf8") #使用cursor()方法获取数据库的操作游标cursor = conn.cursor()cursor.execute("select * from user order by id")print u"当前游标所在位置：", cursor.rownumberres = cursor.fetchmany(5)for value in res:    print valueprint u"当前游标所在位置：", cursor.rownumbercursor.scroll(3,mode="relative")#游标会向前移动3，对应数据库表就是向后移动3行print u"当前游标所在位置：", cursor.rownumberprint cursor.fetchone()

MYSQLDB Operational Database (iii)