SOUNDEX

Syntax

Purpose

SOUNDEX returns a character string containing the phonetic representation of char. This function allows you to compare words that are spelled differently, but sound alike in English.

The phonetic representation is defined in The Art of Computer Programming, Volume 3: Sorting and Searching, by Donald E. Knuth, as follows:

• Retain the first letter of the string and remove all other occurrences of the following letters: a, e, h, i, o, u, w, y.

• Assign numbers to the remaining letters (after the first) 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
  
  

• If two or more letters with the same number were adjacent in the original name (before step 1), or adjacent except for any intervening h and w, omit all but the first.

• Return the first four bytes padded with 0.

Example

SELECT ename
     FROM emp
     WHERE SOUNDEX(ename)
         = SOUNDEX('SMYTHE');

ENAME
----------
SMITH