oracle 生成指定长度字符串的函数

最近在写一个小程序，需要获取指定长度的字符串  number float time等类型的数据，所以自己封装了一个函数

#生成指定长度的字符串
def random_char(length,flag):#flag为0表示number,1表示字符串类型,2表示time类型 
    
    result = ''
    chars = 'AaBbCcDdEeFfGgHhIiJjKkLlMmNnOoPpQqRrSsTtUuVvWwXxYyZz0123456789'
    nums = '123456789'
    numlength = len(nums) - 1
    charlength = len(chars) - 1
    str_tmp = Random()
    
    if flag == 1:
        result = datetime.datetime.now().strftime("%Y-%m-%d %H:%M:%S")
        return result
    elif flag == 2:
        result = datetime.datetime.now().strftime("%Y-%m-%d %H:%M:%S.%f")
        return result
    elif flag == 3 or flag == 4:
        for i in range(int(length)):
            if flag == 3: #1表示date,2表示timestamp,3表示number,4表示varchar2 nvarchar2 long char,5表示float
                result += nums[str_tmp.randint(0,numlength)]
            elif flag == 4:
                result += chars[str_tmp.randint(0,charlength)] 
    elif flag == 5:#length == P20S8 即PRECISION = 20   SCALE = 8
        precision,scale = get_precision_scale(length)
        integer_max = int(precision) - int(scale)
        for j in range(integer_max):
            result += nums[str_tmp.randint(0,numlength)]
        result += '.'
        for k in range(int(scale)):
            result += nums[str_tmp.randint(0,numlength)]
            
    return result