How Can I Correctly Format Phone Numbers with Multiple Plus Signs in SQL?

As someone who frequently works with database management, I often deal with data normalization issues, including phone number formatting. Recently, I encountered a scenario where phone numbers in a database were inconsistently formatted, some with multiple plus signs (+). Correcting this to ensure a uniform format is crucial for data integrity and ease of use. Let’s discuss how to tackle this with SQL, improving upon the query mentioned.

Initial Observation

The initial query provided attempts to clean up the phone number by removing certain special characters and leading zeros using a combination of TRIM, LEADING, and REGEXP_REPLACE functions:

replace((TRIM(LEADING '0' FROM (REGEXP_REPLACE(channel_value, '[\]\\[!@#$%.&*~^_{}:;<>/\\|()+-]', '')))),' ' ,'')

This script strips various special characters and leading zeros but doesn’t correctly address the issue of multiple plus signs. Let’s break this issue down and solve it step by step.

Understanding the Problem

Phone numbers in the database are prefixed with one or more plus signs, possibly surrounded by parentheses. The goal is to standardize these to have just one single plus sign at the beginning, maintaining other essential formatting like spaces and parentheses that might segment country codes or area codes.

Crafting the Solution

To achieve the desired outcome, I suggest a two-step approach:

1. Normalize the Plus Signs: Ensure only one plus sign remains at the beginning of each phone number.

1. Maintain Other Formatting: Keep spaces, parentheses, and numbers as they are essential for the phone number’s readability and structure.

Here’s how you can accomplish this:

1. Replace Multiple Plus Signs: Use REGEXP_REPLACE to change all sequences of one or more plus signs to a single plus sign.

1. Trim and Remove Unnecessary Characters: Further use REGEXP_REPLACE to trim unwanted characters while keeping essential formatting.

Here’s the revised SQL query:

SELECT 
    REGEXP_REPLACE(
        REGEXP_REPLACE(channel_value, '\+{1,}', '+'),  -- Replace multiple plus signs with a single plus sign
        '[^\d\+\(\) ]',                               -- Remove unwanted characters, allowing digits, plus signs, parentheses, and spaces
        ''
    ) AS formatted_phone_number
FROM
    your_table_name;

Explanation

• \+{1,}: This regex pattern matches sequences of one or more plus signs, replacing them with a single plus.

• [^\d\+\(\) ]: This pattern keeps digits (\d), plus signs (\+), parentheses (\( or \)) and spaces, removing all other characters that are not required.

Test It Out

Let’s apply this to the sample phone numbers from your question:

• Before: (+) (+911) 24234324324324

• After: (+911) 24234324324324

• Before: ++091787534 5303

• After: +091787534 5303

• Before: (++91) 9711931220

• After: (+91) 9711931220

This updated SQL query ensures that regardless of how the phone numbers are initially formatted with surplus plus signs or other extraneous characters, they are uniformly formatted as per the requirements. Now, your database will maintain a cleaner, more standardized set of phone numbers, ideal for any systems depending on this data, such as contact management systems or communication platforms.