postgres

History

Neil Conway 1ac9f0e9f7 The attached patch implements the soundex difference function which compares two strings' soundex values for similarity, from Kris Jurka. Also mark the text_soundex() function as STRICT, to avoid crashing on NULL input.		2005-01-26 08:04:04 +00:00
..
Makefile	> Please find enclose a submission to fix these problems.	2004-08-20 20:13:10 +00:00
README.fuzzystrmatch	The attached patch implements the soundex difference function which	2005-01-26 08:04:04 +00:00
README.soundex	The attached patch implements the soundex difference function which	2005-01-26 08:04:04 +00:00
dmetaphone.c	Adjust comments previously moved to column 1 by pgident.	2004-10-07 15:21:58 +00:00
fuzzystrmatch.c	The attached patch implements the soundex difference function which	2005-01-26 08:04:04 +00:00
fuzzystrmatch.h	The attached patch implements the soundex difference function which	2005-01-26 08:04:04 +00:00
fuzzystrmatch.sql.in	The attached patch implements the soundex difference function which	2005-01-26 08:04:04 +00:00

README.soundex

NOTE: Modified August 07, 2001 by Joe Conway. Updated for accuracy
	after combining soundex code into the fuzzystrmatch contrib
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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)\g

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

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

select a.nm, b.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 = #=)\g

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

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

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