SOUNDEX function in Oracle - To compare words that are phonetically similar

The SOUNDEX function in Oracle is used to compare words that are phonetically similar. This function converts a string into a code that represents its sound. Words that sound similar are given the same code, which can be useful in applications such as name matching, data deduplication, and fuzzy searching.

SOUNDEX(string)

Parameters

• string: The string to be converted to its SOUNDEX code.

How SOUNDEX Works

1. The first letter of the string is retained.
2. The remaining letters are converted to digits as follows:
   • B, F, P, V => 1
   • C, G, J, K, Q, S, X, Z => 2
   • D, T => 3
   • L => 4
   • M, N => 5
   • R => 6
3. Adjacent letters that convert to the same digit are reduced to a single digit.
4. Vowels (A, E, I, O, U), H, W, and Y are ignored unless they are the first letter.
5. The resulting code is trimmed to four characters. If necessary, it is padded with zeros.

Example Usage

Here's an example of how to use the SOUNDEX function in Oracle:

SELECT SOUNDEX('Smith') AS soundex_code FROM dual; -- Output: S530 SELECT SOUNDEX('Smythe') AS soundex_code FROM dual; -- Output: S530 SELECT SOUNDEX('Robert') AS soundex_code FROM dual; -- Output: R163 SELECT SOUNDEX('Rupert') AS soundex_code FROM dual; -- Output: R163

Practical Example

Suppose you have a table of employee names, and you want to find names that sound similar to "Smith."

CREATE TABLE employees ( id NUMBER PRIMARY KEY, name VARCHAR2(100) ); INSERT INTO employees (id, name) VALUES (1, 'Smith'); INSERT INTO employees (id, name) VALUES (2, 'Smythe'); INSERT INTO employees (id, name) VALUES (3, 'Johnson'); INSERT INTO employees (id, name) VALUES (4, 'Smithee'); SELECT name FROM employees WHERE SOUNDEX(name) = SOUNDEX('Smith');

This query will return names that sound similar to "Smith," such as "Smythe" and "Smithee."

Considerations

• The SOUNDEX function is designed for English and may not perform as well with names or words in other languages.
• It simplifies phonetic comparisons but might produce the same code for words that are phonetically distinct in different contexts.

By using the SOUNDEX function, you can perform phonetic searches and comparisons in your Oracle database, which can be particularly useful for matching names and other similar text data.