How to use the MySQL SOUNDEX() function

In this article, we will learn how to use the MySQL SOUNDEX() function, which returns the soundex code of a string. The soundex code is a four-character code that represents the pronunciation of a word, based on the English alphabet. We will also see some examples of how to use this function in different situations, and explore some related functions that can be helpful for working with strings and soundex codes.

Syntax

The syntax of the SOUNDEX() function is as follows:

SOUNDEX(str)

The str parameter can be any string expression. If the str parameter is NULL, the function returns NULL. The SOUNDEX() function returns a four-character string that represents the soundex code of the given string. The soundex code is composed of the first letter of the string, followed by three digits that encode the remaining consonants. The vowels and the letters H, W, and Y are ignored, unless they are the first letter. The same soundex code is assigned to words that have similar pronunciations. For example, SOUNDEX('Smith') and SOUNDEX('Smyth') both return ‘S530’.

Examples

Let’s see some examples of how to use the SOUNDEX() function in MySQL.

Example 1: Get the soundex code of a string

We can use the SOUNDEX() function to get the soundex code of a string. For example:

SELECT SOUNDEX('Hello') AS result;

This query will return the soundex code of the string ‘Hello’. The query will return ‘H400’, which represents the pronunciation of the word.

Example 2: Compare the soundex codes of two strings

We can use the SOUNDEX() function with the = operator to compare the soundex codes of two strings. For example:

SELECT SOUNDEX('Hello') = SOUNDEX('Halo') AS result;

This query will compare the soundex codes of the strings ‘Hello’ and ‘Halo’. The query will return 1, since the soundex codes are the same.

Example 3: Find the words that have the same soundex code as a given word

We can use the SOUNDEX() function with the IN operator and a subquery to find the words that have the same soundex code as a given word in a table. For example, suppose we have a table called words that stores some English words, with the following column:

• word: the word

We can use the following query to find the words that have the same soundex code as the word ‘Hello’ in the table:

SELECT word
FROM words
WHERE SOUNDEX(word) IN (SELECT SOUNDEX('Hello'));

This query will return the words that have the same soundex code as the word ‘Hello’ in the table. For example, the query might return something like this:

Example 4: Find the words that sound similar to a given word

We can use the SOUNDEX() function with the LIKE operator and a wildcard to find the words that sound similar to a given word in a table. For example, suppose we have a table called words that stores some English words, with the following column:

• word: the word

We can use the following query to find the words that sound similar to the word ‘Hello’ in the table:

SELECT word
FROM words
WHERE SOUNDEX(word) LIKE CONCAT(SOUNDEX('Hello'), '%');

This query will return the words that sound similar to the word ‘Hello’ in the table. The query will use the CONCAT() function to append a wildcard to the soundex code of the word ‘Hello’, and then use the LIKE operator to match the soundex codes that start with the same prefix. For example, the query might return something like this:

Example 5: Get the difference between the soundex codes of two strings

We can use the SOUNDEX() function with the SOUNDS_LIKE() function, which returns the difference between the soundex codes of two strings, to get the difference between the soundex codes of two strings. For example:

SELECT SOUNDS_LIKE(SOUNDEX('Hello'), SOUNDEX('World')) AS result;

This query will return the difference between the soundex codes of the strings ‘Hello’ and ‘World’. The query will return 4, since the soundex codes are different in all four positions.

Related Functions

There are some other functions that are related to the SOUNDEX() function, and can be useful for working with strings and soundex codes. Here are some of them:

• SOUNDS_LIKE(): This function returns the difference between the soundex codes of two strings. For example, SOUNDS_LIKE(SOUNDEX('Hello'), SOUNDEX('World')) returns 4.
• SOUNDS LIKE: This operator is a synonym for the SOUNDEX() function with the = operator. For example, SOUNDEX('Hello') SOUNDS LIKE SOUNDEX('Halo') returns 1.
• SUBSTRING(): This function returns a substring of a string, starting from a specified position and with a specified length. For example, SUBSTRING('Hello', 2, 3) returns ’ell’.
• LENGTH(): This function returns the length of a string in bytes. For example, LENGTH('Hello') returns 5.
• CONCAT(): This function returns the concatenation of two or more strings. For example, CONCAT('Hello', ' ', 'World') returns ‘Hello World’.

Conclusion

In this article, we learned how to use the MySQL SOUNDEX() function, which returns the soundex code of a string. We also saw some examples of how to use this function in different situations, and explored some related functions that can be helpful for working with strings and soundex codes.