练习 python之数据库增删改查

# 文件存储时可以这样表示

#
# id,name,age,phone,dept,enroll_date
# 1,Alex Li,22,13651054608,IT,2013-04-01
# 2,Jack Wang,28,13451024608,HR,2015-01-07
# 3,Rain Wang,21,13451054608,IT,2017-04-01
# 4,Mack Qiao,44,15653354208,Sales,2016-02-01
# 5,Rachel Chen,23,13351024606,IT,2013-03-16
# 6,Eric Liu,19,18531054602,Marketing,2012-12-01
# 7,Chao Zhang,21,13235324334,Administration,2011-08-08
# 8,Kevin Chen,22,13151054603,Sales,2013-04-01
# 9,Shit Wen,20,13351024602,IT,2017-07-03
# 10,Shanshan Du,26,13698424612,Operation,2017-07-02
# 可进行模糊查询，语法至少支持下面3种查询语法:
#
# select name,age from staff_table where age > 22
# select * from staff_table where dept = "IT"
# select * from staff_table where enroll_date like "2013"
# 可创建新员工纪录，以phone做唯一键(即不允许表里有手机号重复的情况)，staff_id需自增语法:
#
# add to staff_table values Alex Li,25,134435344,IT,2015-10-29
# 可删除指定员工信息纪录，输入员工id，即可删除语法:
#
# del from staff_table where id = 3
# 可修改员工信息，语法如下:
#
# update staff_table set dept = Market where dept = IT #把所有dept=IT的纪录的dept改成Market
# update staff_table set age = 25 where name = Alex Li #把name=Alex Li的纪录的年龄改成25
# 以上每条语名执行完毕后，要显示这条语句影响了多少条纪录。比如查询语句就显示查询出了多少条、修改语句就显示修改了多少条等。
# 注意：以上需求，要充分使用函数，请尽你的最大限度来减少重复代码！

版本：python3.6


新建主体函数 databases.py

import re
import select_mo
import del_mo
import update_mo

#operation = input('请输入你要操作的指令 ：').lower()
operation = 'select name,age   , phone  from where age < 23'
SELECT = re.search('^select', operation)
DEL = re.search('^del', operation)
UPDATE = re.search('^update', operation)

data = {'id': 0, 'name': 1, 'age': 2, 'phone': 3, 'dept': 4, 'enroll_date': 5}

if SELECT:
    select_mo.SELECT(operation, data)

elif DEL:
    del_mo.DEL(operation, data)

elif UPDATE:
    update_mo.UPDATE(operation, data)

else:
    print('你输入的指令不正确')

新建查的脚本：select_mo.py
def SELECT(operation, data):
    # select name,age from  where age > 22
    # select * from  where dept = "IT"
    # select * from  where enroll_date like "2013"
    # 1,Alex Li,22,13651054608,IT,2013-04-01

    def print_name():
        name = ''
        for SCREEN in screen_list:
            name += ' ' + data_list[data[SCREEN]]
        print(name)

    check, term = operation.split('from')
    screen = check.replace('select', '')
    if 'where' in term:
        term_total = term.replace('where', '')
        if '>' in term_total:
            term, tail = term_total.split('>')
        elif '<' in term_total:
            term, tail = term_total.split('<')
        elif '=' in term_total:
            term, tail = term_total.split('=')
            tail = tail.replace('"','')
        elif 'like' in term_total:
            term, tail = term_total.split('like')
            tail = tail.replace('"', '')
        else:
            exit('没有条件')
        term = term.strip()
        tail = tail.strip()

    screen_list = []
    if '*' in screen:
        screen_list = list(data)
    elif ',' in screen:
        screen_list = screen.split(',')
        for i in range(len(screen_list)):
            screen_list[i] = screen_list[i].strip()
    else:
        screen_list.append(screen.strip())

    with open('database.txt') as DATA:
        for i in DATA:
            data_list = []
            data_list = i.split(',')
            for i in range(len(data_list)):
                data_list[i] = data_list[i].strip()
            #print(data_list)
            if '>' in term_total:
                if int(data_list[data[term]]) > int(tail):
                    print_name()
            elif '<' in term_total:
                if int(data_list[data[term]]) < int(tail):
                    print_name()
            elif '=' in term_total and not data_list[data[term]].isdigit():
                if data_list[data[term]] == tail:
                    print_name()
            elif '=' in term_total and data_list[data[term]].isdigit():
                if int(data_list[data[term]]) == int(tail):
                    print_name()
            elif 'like' in term_total:
                if tail in data_list[data[term]]:
                    print_name()

if __name__ == '__main__' :
    data = {'id': 0, 'name': 1, 'age': 2, 'phone': 3, 'dept': 4, 'enroll_date': 5}
    operation = 'select * from  where enroll_date like "2013"'
    SELECT(operation, data)