postgresql/contrib/fuzzystrmatch/README.soundex

NOTE: Modified August 07, 2001 by Joe Conway. Updated for accuracy
	after combining soundex code into the fuzzystrmatch contrib
---------------------------------------------------------------------
The Soundex system is a method of matching similar sounding names
(or any words) to the same code.  It was initially used by the
United States Census in 1880, 1900, and 1910, but it has little use
beyond English names (or the English pronunciation of names), and
it is not a linguistic tool.

The following are some usage examples:

SELECT soundex('hello world!');

CREATE TABLE s (nm text)\g

insert into s values ('john')\g
insert into s values ('joan')\g
insert into s values ('wobbly')\g

select * from s
where soundex(nm) = soundex('john')\g

select nm from s a, s b
where soundex(a.nm) = soundex(b.nm)
and a.oid <> b.oid\g

CREATE FUNCTION text_sx_eq(text, text) RETURNS bool AS
'select soundex($1) = soundex($2)'
LANGUAGE 'sql'\g

CREATE FUNCTION text_sx_lt(text,text) RETURNS bool AS
'select soundex($1) < soundex($2)'
LANGUAGE 'sql'\g

CREATE FUNCTION text_sx_gt(text,text) RETURNS bool AS
'select soundex($1) > soundex($2)'
LANGUAGE 'sql';

CREATE FUNCTION text_sx_le(text,text) RETURNS bool AS
'select soundex($1) <= soundex($2)'
LANGUAGE 'sql';

CREATE FUNCTION text_sx_ge(text,text) RETURNS bool AS
'select soundex($1) >= soundex($2)'
LANGUAGE 'sql';

CREATE FUNCTION text_sx_ne(text,text) RETURNS bool AS
'select soundex($1) <> soundex($2)'
LANGUAGE 'sql';

DROP OPERATOR #= (text,text)\g

CREATE OPERATOR #= (leftarg=text, rightarg=text, procedure=text_sx_eq,
commutator=text_sx_eq)\g

SELECT *
FROM s
WHERE text_sx_eq(nm,'john')\g

SELECT *
from s
where s.nm #= 'john';