【Python】拼接MySQL常用语句

import pymysql

class MK_sql ():
    """
    构建mySQL常见语句：增删改查排序
    """

    def __init__(self, table_name):
        self.table_name = table_name

    def mk_create(self, value: list):
        """
        构建mySQL创建表语句
        @param value: 字段列表
        @return:
        """
        if not isinstance (value, list):
            raise Exception ("TypeError")
        sql = "create table %s (%s)" % (self.table_name, self.to_str (value))
        return sql

    def mk_delete(self, condition: dict):
        """
        构建mySQL删除指定字段语句
        @param condition: 删除条件，dict型
        @return:
        """
        if not isinstance (condition, dict):
            raise Exception ("TypeError")
        sql = "delete from %s" % self.table_name
        sql += " where %s " % self.to_str_and (condition)
        return sql

    def mk_insert(self, value: list):
        """
        构建mySQL插入字段语句
        @param value: 需插入的整行数据
        @return:
        """
        if not isinstance (value, list):
            raise Exception ("TypeError")
        sql = "insert into %s values " % self.table_name
        sql += str (value)
        return sql

    def mk_update(self, value: dict, condition: dict):
        """
        构建mySQL更新字段语句
        @param value: dict 要更新的字段
        @param condition: dict SQL条件语句
        @return:
        """
        if not isinstance (value, dict) or not isinstance (condition, dict):
            raise Exception ("TypeError")
        sql = "update %s set " % self.table_name
        sql += self.to_str (value)
        sql += " where %s " % self.to_str_and (condition)
        return sql

    def mk_select(self, cols=None, limit=None, distinct=False):
        """
        构建mySQL select查询语句
        @param cols: list型，要查询的字段名称
        @param limit: int型
        @param distinct: bool型，True:去重，只作用于非全部查询
        @return:
        """
        if (cols != None and not isinstance (cols, list)) or \
                (limit !=None and not isinstance (limit, int)) or not isinstance(distinct,bool):
            raise Exception ("TypeError")

        if not limit:
            if not cols:
                sql = "select * from %s" % self.table_name
            else:
                if not distinct:
                    sql = "select %s from %s" % (self.to_str (cols), self.table_name)
                else:
                    sql = "select distinct %s from %s" % (self.to_str (cols), self.table_name)
            return sql
        else:
            if not isinstance (limit, int):
                raise Exception ("TypeError")
            if not cols:
                sql = "select * from %s limit %s" % (self.table_name, limit)
            else:
                if not distinct:
                    sql = "select %s from %s limit %s" % (self.to_str (cols), self.table_name, limit)
                else:
                    sql = "select distinct %s from %s limit %s" % (self.to_str (cols), self.table_name, limit)
            return sql

    def mk_order_by(self, value: list, asc=True):
        """
        构建mySQL排序语句
        @param value: 单个字段或多个字段
        @param asc: 默认为True升序，FALSE为降序
        @return:
        """
        if not isinstance (value, list) or not isinstance(asc,bool):
            raise Exception ("TypeError")
        if asc:
            sql = "order by %s from %s" % (self.to_str (value), self.table_name)
        else:
            sql = "order by %s from %s desc" % (self.to_str (value), self.table_name)
        return sql

    def to_str_and(self, value: dict):
        """
        内部函数，用于转换mySQL带and条件语句
        @param value:dict型
        @return: [key='value' and key='value' and...]
        """
        info_list = ["%s='%s'" % (str (k), str (v)) for k, v in value.items ()]
        return " and ".join (info_list)

    def to_str(self, value):
        """
        内部函数，转换成SQL指定的str格式
        @param value: list/dict
        @return: 1、list参数不带引号的str，2、dict参数返回[key='value', key='value'...]
        """
        if isinstance (value, list):
            cnt = ["%s" % value for value in value]
            return ",".join ((cnt))
        elif isinstance (value, dict):
            cnt = ["%s='%s'" % (str (k), str (v)) for k, v in value.items ()]
            return ",".join (cnt)