如何从SQL记录的电话号码中删除领先的国家代码？

Question

I am currently trying to figure out how to remove the leading country code from some phone number records within my SQL query. Essentially, some of the records that I am selecting have either a 1 (US) or 44 (UK) country code in front of the number. I would like to be able to detect which records have this country code and then separate it into a separate column. Here is the current query that pulls the phone number data:

SELECT REPLACE(REPLACE(REPLACE(REPLACE(tbl_vsed_unvalidated.telephonenumber,'#',null),'-',null),' ',null),'+',null)
   AS "PHONE 1"

This query is pulling the data from a telephonenumber table column in the database and then stripping any #,-, and spaces. In order to try removing the country codes, I was considering making use of something like this:

If(len>10){trim(Leading "1" from "PHONE 1")}

Would something like this work? Also how would I be able to store this 1 into a new entity called "PHONE 1 COUNTRY CODE"?

Eventually I would need to be able to remove a trailing extension from records as well, but I assume that would be a similar process. (Ex. if the number is 180012345671234, I would need to be able to strip the leading "1" and the trailing "1234" and store them each in new separate columns.

Thanks for any help!

Pete

Answer 1

What i would suggest is

a for loop that goes through each number and detects the length if its +44 (UK) its going to be x length

if its US it will be y length

see if you can write something to match that up

then once you have a rough match, see if you can trim the numbers off while still in that loop.

Answer 2

This is a basic example of using CASE to work through the phone numbers by lengtht. You will have to change the lengths to suit your reality. If your phone numbers have + or parens, etc, you should normalize them first so what remains is a string of numbers. As for the phones with extensions, they will show under the 'ELSE' clause and you can work out how to deal with them later, as you said. Hopefully this will at least get you started.

SELECT 
   CASE phone
      WHEN Length(phone) = 10 THEN phone
      WHEN Length(phone)  = 11 THEN substr(phone,2)
      WHEN Length(phone)  = 14 THEN substr(phone,4)
      ELSE phone
   END AS Phone from customers