【python】——sql模拟

一.作业需求：

当然此表你在文件存储时可以这样表示

1,Alex Li,22,13651054608,IT,2013-04-01

现需要对这个员工信息文件，实现增删改查操作

1. 可进行模糊查询，语法至少支持下面3种:
   1. 　　select name,age from staff_table where age > 22
   2. 　　select  * from staff_table where dept = "IT"
   3. select  * from staff_table where enroll_date like "2013"
   4. 查到的信息，打印后，最后面还要显示查到的条数
2. 可创建新员工纪录，以phone做唯一键，staff_id需自增
3. 可删除指定员工信息纪录，输入员工id，即可删除
4. 可修改员工信息，语法如下:
   1. 　　UPDATE staff_table SET dept="Market" WHERE where dept = "IT"

 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！

二.流程图

三.代码

1.数据库文件

name：mysql.user

,陈浩元,,,运维,--
,刘阔,,,运维,--
,夏婉婉,,,测试工程师,--
,彭思龙,,,测试攻城狮,--
,党禾迪,,,运维,--
,孙京国,,,运维工程师,--
,王冬,,,运维,--
,章曾,,,运维,--
,陈俊明,,,运维背锅者,--
,戴成旭,,,运维,--
,肖静,,    ,None,--
,王振山,,,运维,--
,韩韬,,    ,系统集成,--
,韩钰柯,,,运维, --
,王兴平,,,运维工程师,--
,崔晓娜,,,运维,--
,田晨超,,,Linux爱好者,--
,张志凡,,,运维工程师,--
,曾志高翔,,,运维,--
,翁建伟,,,无,--
,王华强,,,测试,--
,蔡志亮,,,运维,--
,颜明建,,,打杂,--
,李毅,,,QA,--
,刘振涛,,,高级运维工程师,--
,李善超,,,网络安全,--
,金煜东,,,运维,--
,许晨阳,,,运维,--
,孙克东,,,运维工程师,--
,王朝,,,DBA,--
,段晓冲,,,运维,--
,江帆,,,运维,--
,李众,,,运维工程师,--
,何金刚,,,运维工程师,--
,张美玲,,,linux运维,--
,唐磊,,,测试,--
,黄骁瀚,,,系统工程师,--
,李英琦,,,运维,--
,刘亮亮,,,运维,--
,赵宏宇,,,Linux运维工程师,--
,黄宏伟,,,运维,--
,何玲,,    ,数据分析师,--
,杨建波,,,系统工程师,--
,倪耀毅,,,自动化测试,--
,乔路,,,运维,--
,赵凯,,,运维工程师,--

2.代码

#!/usr/bin/env python
#-*- coding:utf-8 -*-
#Author:__Json.Zzgx__
import os
def sql_cmd(sql):
    parse_func={
        'insert':insert_cmd,
        'delete':delete_cmd,
        'update':update_cmd,
        'select':select_cmd,
    }
    sql_l=sql.split(' ')
    func=sql_l[0]
    res=''
    if func in parse_func:
        res=parse_func[func](sql_l)
    return res

def insert_cmd(sql_1):
    sql_dic={
        'func':insert,
        'into':[],
        'values':[]
    }
    return handle_cmd(sql_1,sql_dic)

def delete_cmd(sql_1):
    sql_dic={
        'func':delete,
        'from':[],
        'where':[]
    }
    return handle_cmd(sql_1,sql_dic)

def update_cmd(sql_1):
    sql_dic={
        'func':update,
        'update':[],
        'set':[],
        'where':[]
    }
    return handle_cmd(sql_1,sql_dic)
def select_cmd(sql_1):
    sql_dic={
        'func':select,
        'select':[],
        'from':[],
        'where':[],
        'limit':[],
    }
    return handle_cmd(sql_1,sql_dic)

def handle_cmd(sql_l,sql_dic):
    tag=False
    for item in sql_l:
        if item in sql_dic:
            tag=True
            key=item
        if tag and item not in sql_dic:
            sql_dic[key].append(item)
    if sql_dic.get('where'):
        sql_dic['where']=where_cmd(sql_dic.get('where'))
    return sql_dic

def where_cmd(where_l):
    res=[]
    key=['and','or','not']
    char=''
    for i in where_l:
        if i not in key:
            char=char+i
        if i in key:
            char=three_cmd(char)
            res.append(char)
            res.append(i)
            char=''
    char = three_cmd(char)
    res.append(char)
    return res

def three_cmd(str):
    key=['>','<','=']
    res=[]
    char=''
    for i in str:
        if i not in key:
            char += i
        if i in key:
            res.append(char)
            res.append(i)
            char=''
    res.append(char)
    if len(res) == 1:
        res=res[0].split('like')
        res.insert(1,'like')
    return res

def sql_action(sql_dic):
    return sql_dic["func"](sql_dic)

def select(sql_dic):
    db=sql_dic["from"][0].strip()
    f=open("%s" %(db),"r",encoding="utf-8")
    where_res=where_action(f,sql_dic["where"])
    f.close()
    limit_res=limit_action(sql_dic["limit"],where_res)
    select_res=select_action(sql_dic["select"],limit_res)
    return select_res

def insert(sql_dic):
    try:
        ph=sql_dic["values"][0].strip("'").split(",")[2]
        ph=sql_dic["values"][0].strip('"').split(",")[2]
    except:
        pass
    sql="select * from mysql.user where phone = %s" %ph
    a=sql_action(sql_cmd(sql))[1]
    if len(a):
        return "你的手机号%s已存在，更换其他手机号!" %ph
    else:
        id=1
        db=sql_dic["into"][0].strip()
        with open("%s" %db,"ab+") as f ,\
                open("%s"%db,'r', encoding="utf-8") as f1:
            for line in f1:
                id=id+1
            try:
                record=sql_dic["values"][0].strip("'").split(",")
                record=sql_dic["values"][0].strip('"').split(",")
            except:
                pass
            record.insert(0,str(id))
            record_new=",".join(record)+"\n"
            f.write(record_new.encode("utf-8"))
            f.flush()
        return "%s插入成功" %record_new

def delete(sql_dic):
    db=sql_dic["from"][0].strip()
    filename="%s" %(db)
    filename_new=db+"_new"
    file=open(filename,'r',encoding="utf-8")
    where_res=where_action(file,sql_dic["where"])
    file.close()
    if len(where_res)==0:
            return "删除记录不存在！"
    else:
        tmp=[]
        for line in where_res:
                tmp.append(line.strip())
        with open(filename,'r',encoding="utf-8") as f,\
                open(filename_new,'w',encoding="utf-8") as f1:
                id = 0
                for f_line in f:
                    if f_line.strip() in tmp:
                        continue
                    else:
                        id=1+id
                        con = f_line.strip("'").split(",")
                        con = f_line.strip('"').split(",")
                        con[0]=str(id)
                        content=",".join(con)
                        f1.write(content)
                f1.flush()
        os.rename(filename,filename+"b")
        os.rename(filename_new,filename)
        os.remove(filename+"b")
        return "共计删除%s条数据" %len(where_res)

def update(sql_dic):
    db=sql_dic["update"][0].strip()
    name="%s" %(db)
    name_new=db+"_new"
    file=open(name,'r',encoding="utf-8")
    records=where_action(file,sql_dic["where"])
    records_new=[]
    file.close()
    set_tmp=sql_dic["set"]
    data_tmp={}
    for i in set_tmp[0].split(","):
        if len(i):
            s=i.split("=")
            try:
                data_tmp[s[0]]=str(s[1].strip("'"))
                data_tmp[s[0]]=str(s[1].strip('"'))
            except:
                pass
    if len(records)==0:
            return "要修改的记录不存在！"
    else:
        for line in records:
                dic={}
                dic['id'],dic['name'],dic['age'],dic['phone'],dic['dept'],dic['date']=line.split(",")
                for data_k in data_tmp:
                    if data_k in dic:
                        dic[data_k]=data_tmp[data_k]
                str_tmp=[]
                for k in dic:
                    str_tmp.append(dic[k])
                records_new.append(str_tmp)
        str_tmp=[]
        for line in records:
            str_tmp.append(line.strip())
        with open(name,'r',encoding="utf-8") as f,\
                open(name_new,'w',encoding="utf-8") as f1:
                for f_line in f:
                    if f_line.strip() in str_tmp:
                        temp=records_new[str_tmp.index(f_line.strip())]
                        temp=",".join(temp)
                        f1.write(temp)
                        continue
                    f1.write(f_line)
                    f1.flush()
        os.rename(name,name+"b")
        os.rename(name_new,name)
        os.remove(name+"b")
        return "共计修改%s条数" %len(records)

def where_action(f,where_sql):
    res=[]
    if len(where_sql):
        for line in f:
            dic={}
            dic['id'], dic['name'], dic['age'], dic['phone'], dic['dept'], dic['date'] = line.split(",")

            logic_res=logic_action(dic,where_sql)
            if logic_res:
                res.append(line)
    else:
        res=f.readlines()

    return res

def logic_action(dic,where_l):
    res=[]
    for i in where_l:
        if type(i) is list:
            a,o,b=i
            if i[1] == '=':
                o="%s=" %i[1]
            dic_v=""
            if dic[a].isdigit():
                    dic_v=int(dic[a])
                    b=int(b)
            else:
                    dic_v="'%s'" %dic[a]
            if o != 'like':
                if type(b)==str:
                    try:
                        b= b.strip("'")
                        b= b.strip('"')
                    except:
                        pass
                    b="'%s'" %b
                i=str(eval("%s%s%s" %(dic_v,o,b)))
            else:
                try:
                   b= b.strip("'")
                   b= b.strip('"')
                except:
                    pass
                if b in dic_v:
                    i='True'
                else:
                    i='False'
        res.append(i)

    res=eval(' '.join(res))
    return res

def limit_action(limit_sql,where_res):
    if len(limit_sql)!=0:
        index=int(limit_sql[0])
        res=where_res[0:index]
    else:
        res=where_res
    return res

def select_action(select_sql,limit_res):
    res=[]
    select_field=select_sql
    if select_sql[0]=="*":
        res=limit_res
        select_field=['id', 'name', 'age', 'phone', 'dept', 'date']
    else:
        for line in limit_res:
            dic={}
            dic['id'], dic['name'], dic['age'], dic['phone'], dic['dept'], dic['date'] = line.split(",")
            r=[]
            for field in select_field[0].split(","):
                r.append(dic[field])
            res.append(",".join(r))
    return [select_field,res]

if __name__ == '__main__':
    print("表名：mysql.user，字段：id,name,age,phone,dept,date")
    while True:
        sql=input("sql> ").strip()
        if sql == 'exit':break
        if len(sql) == 0 :continue
        sql_dic=sql_cmd(sql)
        if len(sql_dic) == 0:continue
        res=sql_action(sql_dic)
        if type(res)==list:
            for line in res[1]:
                print(line.strip())
            print("\n共计查询出%s条数据" %len(res[1]))
        else:
            print(res)

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