SOUNDEX scalar function

Returns a 4-character code representing the sound of the words in the argument. The result can be used to compare with the sound of other strings.

The schema is SYSFUN.

expression

An expression that returns a value of CHAR or VARCHAR data type. The length of the value must not exceed 4 000 bytes. In a Unicode database, if a supplied argument is a graphic string, it is first converted to a character string before the function is executed. The function interprets data that is passed to it as if it were ASCII characters, even if it is encoded in UTF-8.

The result of the function is CHAR(4). The result can be null; if the argument is null, the result is the null value.

The SOUNDEX function is useful for finding strings for which the sound is known but the precise spelling is not. It makes assumptions about the way that letters and combinations of letters sound that can help to search out words with similar sounds. The comparison can be done directly or by passing the strings as arguments to the DIFFERENCE function.

Example

Using the EMPLOYEE table, find the EMPNO and LASTNAME of the employee with a surname that sounds like 'Loucesy'.

   SELECT EMPNO, LASTNAME FROM EMPLOYEE
     WHERE SOUNDEX(LASTNAME) = SOUNDEX('Loucesy')

This example returns the following output:

EMPNO  LASTNAME
------ ---------------
000110 LUCCHESSI