python学习day5

# _*_ coding:utf-8 _*_

"""
模拟数据库：
表内容：
1,Alex,22,13651054608,IT
2,Egon,23,13304320533,Tearcher
3,ding,23,18311028091,IT
表结构：
KEYS = ["id", "name", "age", "phone", "job"]
只有一个信息表，表名：table
增，语法：add from table ding,23,18311028091,IT
删，语法：del from table where id=3
改，语法：update table set age = 23 where name=ding
查，语法：select from table where age=22
          select * from table where age=22
          select * from table

"""

import os
db_file = "table"
KEYS = ["id", "name", "age", "phone", "job"]


def print_log(msg, log_type="info"):
    if log_type == "info":
        print(msg)
    elif log_type == "error":
        print("\033[31;1m%s\033[0m" % msg)


def load_db(db_file):
    """
    加载员工信息表，加载成字典格式
    :param db_file:
    :return:
    """
    info = {}
    for i in KEYS:
        info[i] = []
    with open(db_file, encoding="utf-8") as f:
        for line in f:
            cust_id, name, age, phone, job = line.split(",")
            info["id"].append(cust_id)
            info["name"].append(name)
            info["age"].append(age)
            info["phone"].append(phone)
            info["job"].append(job)
        return info


DATA = load_db(db_file)



def method_gt(column, condtion_val):
    """
    ">"方法
    :param column:listing
    :param val:值
    :return:
    """
    user_info = []
    for index,val in enumerate(DATA[column]):
        if float(val) > float(condtion_val):
            record = []
            for col in KEYS:
               record.append(DATA[col][index])
            user_info.append(record)
    return user_info




def method_lt(column, condtion_val):
    """
    "<"方法
    :param column:
    :param condtion_val:
    :return:
    """
    user_info = []
    for index,val in enumerate(DATA[column]):
        if float(val) < float(condtion_val):
            record = []
            for col in KEYS:
               record.append(DATA[col][index])
            user_info.append(record)
    return user_info

def method_eq(column, condtion_val):
    """
    "="方法
    :param column:
    :param condtion_val:
    :return:
    """
    user_info = []
    for index,val in enumerate(DATA[column]):
        if val == condtion_val:
            record = []
            for col in KEYS:
               record.append(DATA[col][index])
            user_info.append(record)
    return user_info

def method_like(column, condtion_val):
    """
    "like"方法
    :param column:
    :param condtion_val:
    :return:
    """
    user_info = []
    for index,val in enumerate(DATA[column]):
        if condtion_val in val:
            record = []
            for col in KEYS:
               record.append(DATA[col][index])
            user_info.append(record)
    return user_info

def way_where(clause):
    """
    解析where条件，并过滤数据
    :param clause:
    :return:
    """
    method = {
        ">": method_gt,
        "<": method_lt,
        "=": method_eq,
        "like": method_like
    }
    for method_key, method_func in method.items():
        if method_key in clause:
            column, val = clause.split(method_key)
            user_data = method_func(column.strip(), val.strip())
            return user_data
    else:
        print_log("语法错误：where条件只支持[>,<,=,like]", "error")


def sql_parser(choise):
    """
    解析sql语句
    :param choise:
    :return:
    """
    way_list = {
        "select":way_select,
        "add":way_add,
        "update":way_update
    }
    if choise.split()[0] in ("add", "del", "update", "select"):
        if "where" in choise:
            query_clause, where_clause = choise.split("where")
            way_where(where_clause)
            user_data = way_where(where_clause)
        else:
            user_data = []
            for index,cust_id in enumerate(DATA["id"]):
                data = []
                for col in KEYS:
                    data.append(DATA[col][index])
                user_data.append(data)
            query_clause = choise
        choise_action = choise.split()[0]
        if  choise_action in way_list:
            way_list[choise_action](user_data,query_clause)
        elif choise.split()[0] == "del":
            way_delete(user_data,choise)
    else:
        print_log(
            "语法错误:[add\\del\\update\\select] from [table] [where] [listing] [>,<,=,like] [val]\n",
            "error")


def way_add(date_set,query_clause):
    """
    对员工信息表添加数据
    语法：add from table ding,23,18311028091,IT
    :param date_set:
    :param query_clause:
    :return:
    """


    choise_way = query_clause.split("from")[0].strip()
    choise_val = query_clause.split(db_file)[1].strip()
    if choise_way == "add" and len(choise_val) > 1:
        with open(db_file,encoding="utf-8",mode="a") as f1:
            choise_id = id + 1
            choise_id_1 = str(choise_id)
            f1.write(choise_id_1)
            f1.write(",")
            f1.write(choise_val)
            f1.close()
            print("添加%s成功！"% choise_val)




def way_select(data_set,query_clause):
    """
    解析查询语句并从data_set打印指定的列
    语法：select from table where age=22
          select * from table where age=22
          select * from table
    :param date_set:
    :param query_clause:
    :return:
    """
    columns = query_clause.split("from")[0][6:].split(",")
    cols = [i.strip() for i in columns]
    if '*' in cols[0]:
        print(data_set)
    else:
        format_data_set = []
        for listing in data_set:
            col_vals = []  #把要打印的字段放在这个列表里
            for col in cols:
                col_index = KEYS.index(col) #拿到每条记录的索引和对应的值
                col_vals.append( listing[col_index] )
            format_data_set.append(col_vals)
        for i in format_data_set:
            print(i)

def read():
    with open(db_file, encoding="utf-8", mode="r") as f:
        lines = f.readlines()
        last_line = lines[-1]
        last_id = last_line[0]
        last_id_1 = int(last_id)
        f.close()
    return last_id_1
id = read()
def way_delete(data_set,choise):
    """
    根据"id"号删除整行数据
    del from table where id=3
    :param date_set:
    :param query_clause:
    :return:
    """
    columns = choise.split("where")[1].split("=")[1]
    columns_id = int(columns)
    if columns in DATA["id"]:
        with open(db_file,encoding="utf-8",mode="r") as f:
            user_info = []
            for i in f:
                r = i.strip().split("\n")
                user_info.append(r)
            user_info.pop(columns_id-1)
            f.close()
        with open("%s.new" % db_file, encoding="utf-8", mode="w") as f1:
            for w in user_info:
                str = ",".join(w)
                f1.write(str+"\n")
            f1.close()
            os.remove(db_file)
            os.rename("%s.new" % db_file, db_file)
            print("删除数据成功！")



    else:
        print_log("输入有误！","error")



        #with open(db_file,encoding="utf-8",mode="w") as f:






def way_update(data_set,query_clause):
    """
    语法：update table set age = 23 where name=ding
    :param date_set:
    :param query_clause:
    :return:
    """
    update_info = query_clause.split("set")
    if len(update_info) > 1:
        col_name,new_val = update_info[1].strip().split("=")
        for matched_row in data_set:
            cust_id = matched_row[0]
            cust_id_index = DATA["id"].index(cust_id)
            DATA[col_name][cust_id_index] = new_val
        save_db()
        print("update" "  "  +col_name+ "=" +new_val+ "  ""数据成功！")


    else:
        print_log("语法错误：未检测到set关键字!","error")


def save_db():
    """
    把修改 在内存中的数据存到硬盘
    :return:
    """
    with open("%s.new"%db_file,encoding="utf-8",mode="w") as f1:
        for index,cust_id in enumerate(DATA["id"]):
            row = []
            for col in KEYS:
                row.append( DATA[col][index])
            f1.write(",".join(row))
        f1.close()
        os.remove(db_file)
        os.rename("%s.new"% db_file,db_file)


def main():
    """
    次函数是用户输入sql语句，调用sql语句方法。
    :return:
    """
    while True:
        choise = input("SQL：").strip()
        if not choise:
            print("输入不能为空，请重新输入。")
            continue
        sql_parser(choise.strip())


main()