作业三：模拟 mysql 进行增删改查

 # !/usr/bin/env python3
 # _*_coding:utf-8_*_

 def help_sql(cmd):
     if cmd in func_dic.keys():
         print('{} usage:\n '.format(cmd))
         if cmd == 'select':
             print("\tselect * from staff_table;")
             print("\tselect name,age from staff_table where age > 22;")
             print("\tselect * from staff_table where dept = \"IT\";")
             print("\tselect * from staff_table where date like \"2013\";")
         elif cmd == 'insert':
             print("\tinsert talbe (Alex Li,22,136510546011,IT,2013-04-01);")
         elif cmd == "update":
             print("\tupdate staff_table set dept = \"Market\" where dept = \"IT\";")
         elif cmd == "delete":
             print("\tdelete table  5;")
     else:
         print('your input ERROR!')
     return

 def input_sql():
     '''
     接受用户输入，做一些判断，转化 list 并一起返回。
     :return:sql
     '''
     exit_flag = False
     while exit_flag is not True:
         sql = input('sql > ').strip()
         sql_list = sql_to_list(sql)
         if sql.startswith('help'):
             cmd = sql_list[1]
             help_sql(cmd)
             continue
         elif sql == 'q' or sql == 'quit' or sql == 'Q' or sql == 'QUIT' or sql == 'exit' or sql == 'EXIT':
             print('已退出程序！')
             exit(1)
         elif len(sql_list) == 0:
             continue
         elif len(sql_list) < 2:
             continue
         elif not (sql.startswith('select') or sql.startswith('insert') or sql.startswith('update') or sql.startswith(
                 'delete')):
             continue
         exit_flag = True
     return sql

 def delete_quotes(str):
     '''
     删掉用户输入的条件值中带双引号。单引号不用去
     :param str:
     :return:
     '''
     if '"' in str:
         str = str.strip('"')
     return str

 def sql_to_list(sql, delimiter=' '):
     '''
     将用户输入的字符串转化为列表的形式，
     :param sql:
     :param delimiter:
     :return:
     '''
     tmp_list = filter(None, sql.split(delimiter))
     sql_list = [item for item in tmp_list]
     return sql_list

 def analyze(sql, table):
     '''
     分析用户输入sql 语句，作用：
     1.拿到 cmd
     2.判断表是否存在
     3.返回命令和要操作的表
     :param sql:
     :param sql_list:
     :param table:
     :return:
     '''
     sql_list = sql_to_list(sql)
     cmd = sql_list[0]
     if sql.startswith('select'):
         sql_table = sql_list[3]
         if sql_table in table:
             return cmd, sql_table
         else:
             return False
     if sql.startswith('insert') or sql.startswith('update') or sql.startswith('delete'):
         sql_table = sql_list[1]
         if sql_table in table:
             return cmd, sql_table
         else:
             return False

             # input_list = sql_to_list(sql)
             # cmd = input_list[0]
             # input_table = input_list[3]
             # if input_table in table:
             #     return cmd, input_table
             # else:
             #     return False

 def file_to_data(sql_table):
     '''
     将文件中的数据读到内存中，以遍读取。这个方法是把所有的数据上来就读进内存中。
     :param sql_table:
     :return:
     '''
     n = 0
     struct_list = []
     data_list = []
     with open(sql_table, 'r', encoding='utf-8') as f:
         for line in f:
             if n == 0:
                 # line = line.strip('\n')
                 struct_list = line.strip('\n').split(',')
             else:
                 # line = line.strip('\n')
                 line_list = line.strip('\n').split(',')
                 data_list.append(line_list)
             n += 1
     return struct_list, data_list

 def data_to_file(struct_list, data_list, table):
     '''
     将内存中的数据写入到文件里
     :param struct_list:
     :param data_list:
     :param table:
     :return:
     '''
     with open(table, 'w', encoding='utf-8') as f:
         f.write(','.join(struct_list) + '\n')
         for sub_list in data_list:
             f.write(','.join(sub_list) + '\n')
         print('Write  Done!')

 def get_cloum_number(colum_name, struct_list):
     '''
     获取列所对应的索引，然后用这个索引在数据项里面取值
     :param colum_name:
     :param struct_list:
     :return:
     '''
     colum_number = struct_list.index(colum_name)
     # print(colum_number)
     return colum_number

 def auto_increament_id(data_list):
     '''
     insert 数据项时，获取新的 id
     :param data_list:
     :return:
     '''
     current_max_id = int(data_list[-1][0])
     new_index_id = current_max_id + 1
     return new_index_id

 # 增删改查阶段
 def select(sql, struct_list, data_list, sql_table):
     sql_list = sql_to_list(sql)
     select_colum = sql_list[1].split(',')
     all_cloum = False
     all_line = False
     if '*' in select_colum:  # 判断输出那些列
         all_cloum = True
     else:
         cloum_numbers_list = []
         for cloum_name in select_colum:
             number = get_cloum_number(cloum_name, struct_list)
             cloum_numbers_list.append(number)

     # 关键字过滤
     select_row = []  # 过滤后的行
     if 'where' in sql:
         condition_column_name = sql_list[5]
         condition_str = sql_list[6]
         condition_value = sql_list[7]
         condition_value = delete_quotes(condition_value)
         condition_column_number = get_cloum_number(condition_column_name, struct_list)

         if condition_str == '=':
             for line in data_list:
                 if line[condition_column_number] == condition_value:
                     select_row.append(line)
         if condition_str == '>':
             for line in data_list:
                 if line[condition_column_number] > condition_value:
                     select_row.append(line)
         if condition_str == '>=':
             for line in data_list:
                 if line[condition_column_number] >= condition_value:
                     select_row.append(line)
         if condition_str == '<':
             for line in data_list:
                 if line[condition_column_number] < condition_value:
                     select_row.append(line)
         if condition_str == '<=':
             for line in data_list:
                 if line[condition_column_number] <= condition_value:
                     select_row.append(line)
         if condition_str == 'like':
             for line in data_list:
                 if condition_value in line[condition_column_number]:
                     select_row.append(line)
     else:
         all_line = True
         select_row = data_list

     # 输出查询的结果
     print('select result:')
     print('#'.center(80, '#'))
     print('\033[1;31;1m{}\033[0m rows in set'.format(len(select_row)))
     if all_cloum is True:
         print('\033[1;34;1m{:<13} {:<13} {:<13} {:<13} {:<13} {:<13}\033[0m'.format(*struct_list))
         for line in select_row:
             print('{:<13} {:<13} {:<13} {:<13} {:<13} {:<13}'.format(*line))
             # print('\t')
     else:
         len_num = len(select_colum)
         format_str1 = '\033[1;34;1m{:13}\033[0m' * len_num
         format_str2 = '{:13}' * len_num
         print(format_str1.format(*select_colum))
         for line in select_row:
             row_list = []
             for s in cloum_numbers_list:
                 row_list.append(line[s])
             print(format_str2.format(*row_list))
     print('#'.center(80, '#'))
     return True

 def insert(sql, struct_list, data_list, sql_table):
     '''
     insert sql : insert   user_info.json  (Liusong Fan,22,13143236545,IT,2015-09-09)
     insert sql : insert   user_info.json  (Liusong Fan,22,13487654567,IT,2015-09-09)
     电话号码作为主键。
     目前只支持插入全部数据项。
     手机号码必须是11位
     :param sql:
     :param struct_list:
     :param data_list:
     :return:
     '''
     tmp_insert = sql_to_list(sql.strip().strip('insert').strip(), '(')
     insert_table = tmp_insert[0].strip()
     insert_info = (tmp_insert[1].strip('(').strip(')'))
     insert_list = insert_info.split(',')

     phone_number = insert_list[2]
     if len(phone_number) != 11:
         print("Phone number wrong(11 numbers), can't insert")
         return False
     phone_exist = False
     for item in data_list:
         if phone_number == item[3]:
             phone_exist = True
     if phone_exist:
         print("Phone number is exist, can't insert")
         return False
     else:
         new_index_id = auto_increament_id(data_list)
         insert_list.insert(0, str(new_index_id))
         data_list.append(insert_list)
     data_to_file(struct_list, data_list, insert_table)

 def delete(sql, struct_list, data_list, sql_table):
     '''
     # delete  table 5
     使用按 id 号删除
     :param ql:
     :param struct_list:
     :param data_list:
     :param sql_table:
     :return:
     '''
     delete_flag = False
     delete_list = sql_to_list(sql.strip())
     delete_index_id = delete_list[2]
     for item in data_list:
         if delete_index_id == item[0]:
             delete_flag = True
             data_list.remove(item)
     if not delete_flag:
         print("ERROE:The delete id is not exist,can't delete")
         return True
     else:
         data_to_file(struct_list, data_list, sql_table)

 def update(sql, struct_list, data_list, sql_table):
     '''
     update user_info.json set dept = "Market" where id = "1"
     set 的值和 where 的值要加"号
     id 是自增的不允许修改，phone 是主键，不允许重复
     set 和 where 只支持 =
     :param sql:
     :param struct_list:
     :param data_list:
     :param sql_table:
     :return:
     '''
     update_list = sql_to_list(sql)
     set_flag = update_list[2]
     modify_column = update_list[3]
     equal_flag = update_list[4]
     modify_value = update_list[5]
     modify_value = delete_quotes(modify_value)
     where_flag = update_list[6]
     condition_column = update_list[7]
     condition_str = update_list[8]
     condition_value = update_list[9]
     condition_value = delete_quotes(condition_value)
     modify_column_number = get_cloum_number(modify_column, struct_list)
     condition_column_number = get_cloum_number(condition_column, struct_list)

     modify_flag = False
     if modify_column == 'id':
         print("ERROR: you can't modify id column value")
         return False
     else:
         if set_flag == 'set' and equal_flag == '=' and where_flag == 'where' and condition_str == '=':
             phone_exists = False
             phone_number = modify_value
             for item in data_list:
                 if phone_number == item[3]:
                     phone_exists = True
             if phone_exists:
                 print("ERROR: you input phone number is exists, can't update")
                 return False
             for d_list in data_list:
                 if d_list[condition_column_number] == condition_value:
                     d_list[modify_column_number] = modify_value
                     modify_flag = True
             if modify_flag:
                 data_to_file(struct_list, data_list, sql_table)
             else:
                 print("ERROR: no match records")
         else:
             print("ERROR: you upate sql error, please input 'help update' get help")

 func_dic = {
     '''
     要操作的数据类型
     '''
     'select': select,
     'update': update,
     'insert': insert,
     'delete': delete,
 }

 def main():
     exit_flag = False
     table = ['user_info.json']
     print('-'.center(60, '-'))
     print('Please input【help [select/update/insert/delete] to get help.')
     print('-'.center(60, '-'))
     while exit_flag is not True:
         sql = input_sql()
         res = analyze(sql, table)
         if not res:
             print('ERROR: your input sql table is not exists!')
             continue
         else:
             cmd = res[0]
             sql_table = res[1]
         struct_list, data_list = file_to_data(sql_table)
         if cmd in func_dic.keys():
             res = func_dic[cmd](sql, struct_list, data_list, sql_table)
             if not res:
                 continue
         else:
             print('ERROR:  your command!')

 if __name__ == '__main__':
     main()