How to format a numeric column as phone number in SQL

Question

I have table in the database with a phone number column. The numbers look like this:

123456789

I want to format that to look like this:

Answer 1

This should do it:

UPDATE TheTable
SET PhoneNumber = SUBSTRING(PhoneNumber, 1, 3) + '-' + 
                  SUBSTRING(PhoneNumber, 4, 3) + '-' + 
                  SUBSTRING(PhoneNumber, 7, 4)

Incorporated Kane's suggestion, you can compute the phone number's formatting at runtime. One possible approach would be to use scalar functions for this purpose (works in SQL Server):

CREATE FUNCTION FormatPhoneNumber(@phoneNumber VARCHAR(10))
RETURNS VARCHAR(12)
BEGIN
    RETURN SUBSTRING(@phoneNumber, 1, 3) + '-' + 
           SUBSTRING(@phoneNumber, 4, 3) + '-' + 
           SUBSTRING(@phoneNumber, 7, 4)
END

Answer 2

I do not recommend keeping bad data in the database and then only correcting it on the output. We have a database where phone numbers are entered in variously as :

• (555) 555-5555
• 555+555+5555
• 555.555.5555
• (555)555-5555
• 5555555555

Different people in an organization may write various retrieval functions and updates to the database, and therefore it would be harder to set in place formatting and retrieval rules. I am therefore correcting the data in the database first and foremost and then setting in place rules and form validations that protect the integrity of this database going forward.

I see no justification for keeping bad data unless as suggested a duplicate column be added with corrected formatting and the original data kept around for redundancy and reference, and YES I consider badly formatted data as BAD data.

Answer 3

Updated @sqiller's function for my purposes

CREATE FUNCTION [toolbox].[FormatPhoneNumber] (
    @PhoneNumber VARCHAR(50),
    @DefaultIfUnknown VARCHAR(50)
)
RETURNS VARCHAR(50)
AS
BEGIN
    -- remove any extension
    IF CHARINDEX('x', @PhoneNumber, 1) > 0
        SET @PhoneNumber = SUBSTRING(@PhoneNumber, 1, CHARINDEX('x', @PhoneNumber, 1) - 1)

    -- cleanse phone number string
    WHILE PATINDEX('%[^0-9]%',@PhoneNumber) > 0
        SET @PhoneNumber = REPLACE(@PhoneNumber,
                SUBSTRING(@PhoneNumber,PATINDEX('%[^0-9]%',@PhoneNumber),1),'')

    -- Remove US international code if exists, i.e. 12345678900
    IF SUBSTRING(@PhoneNumber,1,1) = '1' AND LEN(@PhoneNumber) = 11
        SET @PhoneNumber = SUBSTRING(@PhoneNumber, 2, 10)

    -- any phone numbers without 10 characters are set to default
    IF LEN(@PhoneNumber) <> 10
        RETURN @DefaultIfUnknown

    -- build US standard phone number
    SET @PhoneNumber = '(' + SUBSTRING(@PhoneNumber,1,3) + ') ' +
                SUBSTRING(@PhoneNumber,4,3) + '-' + SUBSTRING(@PhoneNumber,7,4)

    RETURN @PhoneNumber
END

Answer 4

I'd generally recommend you leave the formatting up to your front-end code and just return the data as-is from SQL. However, to do it in SQL, I'd recommend you create a user-defined function to format it. Something like this:

CREATE FUNCTION [dbo].[fnFormatPhoneNumber](@PhoneNo VARCHAR(20))
RETURNS VARCHAR(25)
AS
BEGIN
DECLARE @Formatted VARCHAR(25)

IF (LEN(@PhoneNo) <> 10)
    SET @Formatted = @PhoneNo
ELSE
    SET @Formatted = LEFT(@PhoneNo, 3) + '-' + SUBSTRING(@PhoneNo, 4, 3) + '-' + SUBSTRING(@PhoneNo, 7, 4)

RETURN @Formatted
END
GO

Which you can then use like this:

SELECT [dbo].[fnFormatPhoneNumber](PhoneNumber) AS PhoneNumber
FROM SomeTable

It has a safeguard in, in case the phone number stored isn't the expected number of digits long, is blank, null etc - it won't error.

EDIT: Just clocked on you want to update your existing data. The main bit that's relevant from my answer then is that you need to protect against "dodgy"/incomplete data (i.e. what if some existing values are only 5 characters long)

Answer 5

Above users mentioned, those solutions are very basic and they won't work if the database has different phone formats like:

(123)123-4564
123-456-4564
1234567989
etc

Here is a more complex solution that will work with ANY input given:

CREATE FUNCTION [dbo].[ufn_FormatPhone] (@PhoneNumber VARCHAR(32))
RETURNS VARCHAR(32)
AS
BEGIN
    DECLARE @Phone CHAR(32)

    SET @Phone = @PhoneNumber

    -- cleanse phone number string
    WHILE PATINDEX('%[^0-9]%', @PhoneNumber) > 0
        SET @PhoneNumber = REPLACE(@PhoneNumber, SUBSTRING(@PhoneNumber, PATINDEX('%[^0-9]%', @PhoneNumber), 1), '')

    -- skip foreign phones
    IF (
            SUBSTRING(@PhoneNumber, 1, 1) = '1'
            OR SUBSTRING(@PhoneNumber, 1, 1) = '+'
            OR SUBSTRING(@PhoneNumber, 1, 1) = '0'
            )
        AND LEN(@PhoneNumber) > 11
        RETURN @Phone

    -- build US standard phone number
    SET @Phone = @PhoneNumber
    SET @PhoneNumber = '(' + SUBSTRING(@PhoneNumber, 1, 3) + ') ' + SUBSTRING(@PhoneNumber, 4, 3) + '-' + SUBSTRING(@PhoneNumber, 7, 4)

    IF LEN(@Phone) - 10 > 1
        SET @PhoneNumber = @PhoneNumber + ' X' + SUBSTRING(@Phone, 11, LEN(@Phone) - 10)

    RETURN @PhoneNumber
END

Answer 6

If you want to just format the output no need to create a new table or a function. In this scenario the area code was on a separate fields. I use field1, field2 just to illustrate you can select other fields in the same query:

area  phone
213   8962102

Select statement:

Select field1, field2,areacode,phone,SUBSTR(tablename.areacode,1,3) + '-' + SUBSTR(tablename.phone,1,3) + '-' + SUBSTR(tablename.areacode,4,4) as Formatted Phone from tablename

Sample OUTPUT:

columns: FIELD1, FIELD2, AREA, PHONE, FORMATTED PHONE
data:    Field1, Field2, 213,  8962102,  213-896-2102