2018-11-26 第一周作业

1) 编写一个简单的登录交互系统

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

## 简单的登陆交互系统

cuser = 'admin'
cpwd = 'Passw0rd@00'
user = raw_input("Login User: ")
pwd = raw_input("Login Password: ")
n = 1
while 1:
    if n < 3:
        n += 1
        if user != cuser or pwd != cpwd:
            print "Permission denied, please try again."
            user = raw_input("Login User: ")
            pwd = raw_input("Login Password: ")
        else:
            print "Login successfully."
            break
    else:
        print "You have tried too many times."
        break

2) 模拟SQL语句的增删改查

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

## 每个作业一个包，包里含有readme，描述如何执行

## 模拟mysql查询语句select insert update delete, 表名为user_info

sql = raw_input("Please input sql-statement here: ")
s = sql.lower().split()
f = '/root/user_info'
l = ['id', 'name', 'age', 'class']
ld = []
lf = []
lv = []
l2 = []
if s[0] == 'select' and s[2] == 'from' and s[3].startswith('user_info'):        # 查
    if s[1] == '*':
        with open(f) as fd:
            for line in fd:
                print line,
    elif s[1] in l:
        sn = l.index(s[1])
        with open(f) as fd:
            for line in fd:
                sline = line.split()
                print sline[sn]
    elif s[1].find(',') != -1:
        sd = s[1].split(',')
        snum = len(sd)
        for i in range(snum):
            if l.index(sd[i]) == -1:
                print "%s: this column can't be found " % sd[i]
                break
        for i in range(snum):
           ld.append(l.index(sd[i]))
        with open(f) as fd:
            for line in fd:
                pline = line.split()
                for i in range(snum):
                    print pline[ld[i]],
                print
    else:
        print "Invalid statement"
elif s[0] == 'insert' and s[1] == 'into' and s[2] == 'user_info':       # 增
    r = -1
    lt = lv
    while s[r] != 'user_info':
        l2.append(s[r])
        r -= 1
    l2.reverse()
    s2 = ''.join(l2)
    sp2 = s2.split('values')
    sp2[0] = sp2[0].strip()
    sp2[1] = sp2[1].strip()
    sp2[0] = sp2[0][1:-1].strip()
    sp2[1] = sp2[1][1:-1].strip()
    spf = sp2[0].split(',')
    spv = sp2[1].split(',')
    fn = len(spf)
    for i in range(fn):
        spf[i] = spf[i].strip()
        spv[i] = spv[i].strip()
        if l.index(spf[i]) == -1:
            print "%s: this column can't be found " % spf[i]
            break
    new = []
    for v in l:
        for i in range(fn):
            if spf[i] == v:
                new.append(spv[i])
                i += 1
    newline = '\t'.join(new)
    print newline
    with open(f, 'a') as fd:
        fd.write(newline)

'''
elif s[0] == 'delete' and s[1] == 'from':       # 删
    pass
elif s[0] == 'update' and s[1] == 'user_info' and s[2] == 'set':        # 改
    pass
else:
    print "Invalid statement"
'''