postgres/contrib/fuzzystrmatch
Magnus Hagander 1f2378b1ea Convert cvsignore to gitignore, and add .gitignore for build targets. 2010-09-22 12:57:14 +02:00
..
.gitignore Convert cvsignore to gitignore, and add .gitignore for build targets. 2010-09-22 12:57:14 +02:00
Makefile Simplify contrib Makefiles by removing unnecessary SRCS macro, 2006-10-19 17:40:03 +00:00
README.fuzzystrmatch Update copyright for 2006. Update scripts. 2006-03-05 15:59:11 +00:00
README.soundex Clean up CREATE FUNCTION syntax usage in contrib and elsewhere, in 2006-02-27 16:09:50 +00:00
dmetaphone.c Fix bugs in plpgsql and ecpg caused by assuming that isspace() would only 2006-09-22 21:39:58 +00:00
fuzzystrmatch.c Remove a few baby-C macros in fuzzystrmatch. Add a few missing includes. 2006-07-10 18:40:16 +00:00
fuzzystrmatch.h Defend against non-ASCII letters in fuzzystrmatch code. The functions 2009-04-07 15:54:07 +00:00
fuzzystrmatch.sql.in The attached patch implements the soundex difference function which 2005-01-26 08:04:04 +00:00
uninstall_fuzzystrmatch.sql contrib uninstall scripts 2006-02-27 12:54:39 +00:00

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.

When comparing two soundex values to determine similarity, the
difference function reports how close the match is on a scale
from zero to four, with zero being no match and four being an
exact match.

The following are some usage examples:

SELECT soundex('hello world!');

SELECT soundex('Anne'), soundex('Ann'), difference('Anne', 'Ann');
SELECT soundex('Anne'), soundex('Andrew'), difference('Anne', 'Andrew');
SELECT soundex('Anne'), soundex('Margaret'), difference('Anne', 'Margaret');

CREATE TABLE s (nm text);

INSERT INTO s VALUES ('john');
INSERT INTO s VALUES ('joan');
INSERT INTO s VALUES ('wobbly');
INSERT INTO s VALUES ('jack');

SELECT * FROM s WHERE soundex(nm) = soundex('john');

SELECT a.nm, b.nm FROM s a, s b WHERE soundex(a.nm) = soundex(b.nm) AND a.oid <> b.oid;

CREATE FUNCTION text_sx_eq(text, text) RETURNS boolean AS
'select soundex($1) = soundex($2)'
LANGUAGE SQL;

CREATE FUNCTION text_sx_lt(text, text) RETURNS boolean AS
'select soundex($1) < soundex($2)'
LANGUAGE SQL;

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

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

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

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

DROP OPERATOR #= (text, text);

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

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

SELECT * FROM s WHERE s.nm #= 'john';

SELECT * FROM s WHERE difference(s.nm, 'john') > 2;