Uses the first character in

string

as the first character in the return value and encodes it in uppercase. For example, both SOUNDEX(‘John’) and SOUNDEX(‘john’) return ‘J500’.

Encodes the first three unique consonants following the first character in

string

and ignores the rest. For example, both SOUNDEX(‘JohnRB’) and SOUNDEX(‘JohnRBCD’) return ‘J561’.

Assigns a single code to consonants that sound alike.

The following table lists SOUNDEX encoding guidelines for consonants:

Skips the characters A, E, I, O, U, H, and W unless one of them is the first character in

string

. For example, SOUNDEX(‘A123’) returns ‘A000’ and SOUNDEX(‘MAeiouhwC’) returns ‘M200’.

If

string

produces fewer than four characters, SOUNDEX pads the resulting string with zeroes. For example, SOUNDEX(‘J’) returns ‘J000’.

If

string

contains a set of consecutive consonants that use the same code listed in SOUNDEX, SOUNDEX encodes the first occurrence and skips the remaining occurrences in the set. For example, SOUNDEX(‘AbbpdMN’) returns ‘A135’.

Skips numbers in

string

. For example, both SOUNDEX(‘Joh12n’) and SOUNDEX(‘1John’) return ‘J500’.

Returns NULL if

string

is NULL or if all the characters in

string

are not letters of the English alphabet.