#python 3.6

#统一输出函数，使用distutils.log.warn()函数代替版本2中的print语句和版本3中的print函数

from distutils.log import warn as printf

from random import randrange

#检测内置函数中是否包括raw_input()，如果存在说明版本是2（或者1），不存在说明是3。这样的话，无论是哪个版本，最终scanf函数表示了该功能

if isinstance(__builtins__,dict) and 'raw_input' in __builtins__:

    scanf = raw_input

elif hasattr(__builtins__,'raw_input'):

    scanf = raw_input

else:

    scanf = input

FIELDS = ('login','userid','projid')

COLSIZ = 10

RDBMSs = {'s':'sql server','m':'mysql'}

DBNAME = 'test'

DB_EXC = None

DBUSER = 'root'

DBSERVER = '127.0.0.1'

NAMELEN = 10

tformat = lambda s: str(s).title().ljust(COLSIZ)#str().title()将单词首字母大写；ljust()左对齐，并使用空格填充直至达到指定长度

cformat = lambda s: s.upper().ljust(COLSIZ) #

def setup():

    return RDBMSs[scanf('''

    请选择数据库类型：

    (Sql) Server

    (M)ySQL

    请键入：''').strip().lower()[0]]

def connect(db,DBNAME):

    global DB_EXC

    dbDir = '%s_%s' % (db,DBNAME)

    if db == 'mysql':

        try:

            #python3.0以前的版本

            import MySQLdb

            import _mysql_exceptions as DB_EXC

            try:

                cxn = MySQLdb.connect(user = DBUSER,password = 'Jwxjs123456',db=DBNAME)

            except DB_EXC.OperationalError:

                try:

                    cxn = MySQLdb.connect(user = DBUSER,password = 'Jwxjs123456',db=DBNAME)

                    cxn.query('create database %s' % DBNAME)

                    cxn.commit()

                    cxn.close()

                    cxn = MySQLdb.connect(db=DBNAME)

                except DB_EXC.OperationalError:

                    return None

        except ModuleNotFoundError: #ImportError

            try:

                #python3.0以上的版本

                import pymysql

                import pymysql.err as DB_EXC

                try:

                    cxn = pymysql.connect(**{'host':DBSERVER,'database':DBNAME,'user':DBUSER,'password':'Jwxjs123456'})

                except DB_EXC.InternalError:

                    #连接成功但是没有指定的数据库

                    cxn = pymysql.connect(**{'host':DBSERVER,'user':DBUSER,'password':'Jwxjs123456'})

                    cur = cxn.cursor()

                    cur.execute('create database %s;' % DBNAME)

                    cxn.commit()

                    cxn = pymysql.connect(**{'host':DBSERVER,'database':DBNAME,'user':DBUSER,'password':'Jwxjs123456'})

            except ImportError:

                return None

    elif db == 'sql server':

        import pymssql

        import _mssql

        #import pymssql.StandardError as DB_EXC

        try:

            cxn = pymssql.connect(**{'server':DBSERVER,'database':DBNAME,'password':'Jwxjs123456','user':'sa'})

            printf('     成功链接数据库%s' % DBNAME)

        except BaseException:

            #这里一定要设置为自动提交模式，否则创建数据库会失败

            cxn = pymssql.connect(**{'server':DBSERVER,'password':'Jwxjs123456','user':'sa','autocommit':True})

            cursor = cxn.cursor()

            cxn.commit()

            cursor.execute('create database %s;' % DBNAME)

            #cxn.close()

            cxn = pymssql.connect(**{'server':DBSERVER,'database':DBNAME,'password':'Jwxjs123456','user':'sa','autocommit':True})

            printf('数据库%s 不存在，新建该数据库' % DBNAME)

    return cxn

def create(cur):

    try:

        cur.execute('''

            create table users(login varchar(%s),

                userid int,

                projid int

            )

        ''' % NAMELEN)

        printf('……………新建users表成功')

    except BaseException:

        drop(cur)

        create(cur)

        printf('       已存在表users,删除后并新建此表……………………')

drop = lambda cur:cur.execute('drop table users')

NAMES =(

    ('arron',8312),('angle',7603),('dane',7306),

    ('jess',7912),('jim',7512),('larry',7311),

)

def randName():

    pick = set(NAMES)#内置函数set()创建一个无序不重复元素集，可进行关系测试，删除重复数据，还可以计算交集、差集、并集等

    while pick:

        yield pick.pop()

def insert(cur,db):

    cur.executemany('insert into users values(%s,%s,%s)',[(who,uid,randrange(1,5)) for who,uid in randName()])

#返回最后一次操作影响的行数，这里考虑右边对象是不是支持该属性，不支持的话则返回-1

getRC = lambda cur:cur.rowcount if hasattr(cur,'rowcount') else -1

def update(cur):

    fr = randrange(1,5)

    to = randrange(1,5)

    cur.execute('update users set projid = %s where projid = %s' % (to,fr))

    return fr,to,getRC(cur)

def dbDump(cur):

    cur.execute('select * from users')

    printf('\n%s' % ''.join(map(cformat,FIELDS)))

    for data in cur.fetchall():

        printf(''.join(map(tformat,data)))#join()将序列中的元素以指定的字符连接生成一个新的字符串。

def delete(cur):

    rm = randrange(1,5)

    cur.execute('delete from users where projid = %s' % rm)

    return rm,getRC(cur)

drop = lambda cur:cur.execute('drop table users')

def main():

    #用户选择数据库类型

    db = setup()

    printf('\n****将要连接到 %s(%s) 数据库****' % (DBNAME,db))

    #创建数据库连接

    cxn = connect(db,DBNAME)

    if not cxn:

        printf('\n     连接数据库%s(%s) 失败，程序退出!!!' % (DBNAME,db))

        return

    else:

        printf('\n    成功连接数据库%s(%s)    ' % (DBNAME,db))

    cur = cxn.cursor()

    printf('\n      创建 users表……')

    create(cur)

    printf('\n*****初始化users表******')

    insert(cur,db)

    dbDump(cur)

    printf('\n ***随机更改projid****')

    fr,to,num = update(cur)

    printf('\t(%s 个用户被更改了) from (%s) to(%s)' % (num,fr,to))

    dbDump(cur)

    printf('\n***随机删除某一组数据***')

    rm,num = delete(cur)

    printf('\t(组%s*%s个用户被删除了)' % (rm,num))

    dbDump(cur)

    printf('\n*****删除users表*******')

    drop(cur)

    if db == 'mysql':

        cxn.commit() #sqlserver 的链接已经被设置为自动提交

    printf('\n    关闭数据库连接     ')

    cxn.close()

if __name__ == '__main__':

    main()