REGEXP_REPLACE与DISTINCT

Question

我正在尝试将REGEXP_REPLACE与“ distinct”一起使用，并返回0行。

我已经在MySQLP v8.0中创建了一个测试表

   CREATE TABLE phone(
   id serial primary key,
   phone_number char(25));

   INSERT INTO phone (phone_number)
   VALUES ('(423) 330-9999');

   INSERT INTO phone (phone_number)
   VALUES ('(423)3309999');

   INSERT INTO phone (phone_number)
   VALUES ('423-330-1111)');

   INSERT INTO phone (phone_number)
   VALUES ('1-423-330-6666');

   INSERT INTO phone (phone_number)
   VALUES ('1A423*330*1111');

   INSERT INTO phone (phone_number)
   VALUES ('5553301111');

-然后

select 
   REGEXP_REPLACE(phone_number, '[^0-9]', '',1, 0, 'm') as clean_phone
from phone

---工作正常-> clean_phone 4233309999 4233309999 4233301111 14233306666 14233301111 5553301111

---计数

select 
   count(REGEXP_REPLACE(phone_number, '[^0-9]', '',1, 0, 'm')) as 
   clean_phone
from phone

---工作正常-> clean_phone 6

-不同的clean_phone

select 
   distinct(REGEXP_REPLACE(phone_number, '[^0-9]', '',1, 0, 'm')) as 
   clean_phone
from phone

---返回空-> clean_phone

我不明白为什么区分不起作用？

Answer 1

Distinct不是函数，因此您不需要distinct（），而仅需要

select  distinct REGEXP_REPLACE(phone_number, '[^0-9]', '',1, 0, 'm') as 
   clean_phone
from phone

。

    select distinct  clear_phone from(
    select   REGEXP_REPLACE(phone_number, '[^0-9]', '',1, 0, 'm')  clear_phone
   from phone ) t 

如果错误仍然存​​在，你可以尝试使用插入/选择OFN一个虚表

  insert into dummy_table(clear_phone)
  select   REGEXP_REPLACE(phone_number, '[^0-9]', '',1, 0, 'm')  
  from phone;

  select distinct clear_phone from dummy_table;