SQL SOUNDEX()

The SQL SOUNDEX() function generates a phonetic representation of a string, allowing for similarity matching of words based on how they sound rather than exact spelling. This function is particularly useful for matching names or other text data where variations in spelling can occur but sound similar.

The SOUNDEX() function is supported by SQL Server, MySQL, and other SQL databases.

In this tutorial, we will go through SQL SOUNDEX() String function, its syntax, and how to use this function in SQL statements for string operations, with the help of well detailed examples.

Syntax of SQL SOUNDEX() Function

The basic syntax of the SQL SOUNDEX() function is:

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SOUNDEX(string);

Each part of this syntax has a specific purpose:

  • string: The text or word for which you want to generate a phonetic representation. This can be a column, variable, or text literal.

The SOUNDEX() function returns a four-character code where the first letter is the same as the input, followed by three numbers that represent similar sounds.

Setup for Examples: Creating the Database and Table

We’ll create a sample customers table with a name field to demonstrate the SOUNDEX() function examples.

1. First, create a new database called business:

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CREATE DATABASE business;

2. Select the business database to work with:

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USE business;

3. Create a table named customers with the name field:

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CREATE TABLE customers (
    customer_id INT PRIMARY KEY AUTO_INCREMENT,
    name VARCHAR(100)
);

4. Insert sample data into the customers table to use with the SOUNDEX() function examples:

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INSERT INTO customers (name)
VALUES ('John'), ('Jon'), ('Jonathan'), ('Johan'), ('Jane'), ('Janet'), ('Joan');
SQL SOUNDEX() - Setup for Examples

With this setup complete, you can run the SOUNDEX() function examples to test and view results in the customers table.

Examples: Using SOUNDEX() in SQL Queries

We’ll go through examples demonstrating the SOUNDEX() function in SQL, using sample data from a customers table with a name column.

customers table data for examples

1. Generating SOUNDEX Codes for Customer Names

To generate the SOUNDEX code for each name in the name column:

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SELECT name, SOUNDEX(name) AS soundex_code
FROM customers;

This query returns each name along with its SOUNDEX code, which can be used for comparing similar-sounding names.

SQL SOUNDEX() - Example: Generating SOUNDEX Codes for Customer Names

2. Using SOUNDEX() to Find Similar-Sounding Names

To find customers whose names sound similar to “John”:

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SELECT name
FROM customers
WHERE SOUNDEX(name) = SOUNDEX('John');

This query retrieves names with SOUNDEX codes that match “John,” helping to identify similar-sounding names such as “Jon” or “Johan.”

SQL SOUNDEX() - Example: Using SOUNDEX() to Find Similar-Sounding Names

3. Using SOUNDEX() for Data Standardization

To group similar-sounding names for reporting or standardization:

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SELECT SOUNDEX(name) AS soundex_code, COUNT(*) AS name_count
FROM customers
GROUP BY SOUNDEX(name)
ORDER BY name_count DESC;

This query groups names by SOUNDEX code, allowing you to identify and count similar-sounding names in the dataset.

SQL SOUNDEX() - Example: Using SOUNDEX() for Data Standardization

FAQs for SQL SOUNDEX()

1. What does the SQL SOUNDEX() function do?

The SOUNDEX() function generates a phonetic code representing the sound of a string, useful for matching words based on pronunciation.

2. Can SOUNDEX() handle NULL values?

If the input is NULL, SOUNDEX() returns NULL.

3. Is SOUNDEX() case-sensitive?

No, SOUNDEX() is not case-sensitive. It processes strings in a case-insensitive manner.

4. Is SOUNDEX() supported in all SQL databases?

Yes, SOUNDEX() is supported in major databases like SQL Server, MySQL, and Oracle.

5. Can SOUNDEX() be used to find exact matches?

No, SOUNDEX() is for approximate matches based on sound. For exact matches, use = or LIKE.