How do I do a fuzzy match of company names in MYSQL with PHP for auto-complete?

My users will import through cut and paste a large string that will contain company names.

I have an existing and growing MYSQL database of companies names, each with a unique company_id.

I want to be able to parse through the string and assign to each of the user-inputed company names a fuzzy match.

Right now, just doing a straight-up string match, is also slow. ** Will Soundex indexing be faster? How can I give the user some options as they are typing? **

For example, someone writes:

Microsoft       -> Microsoft
Bare Essentials -> Bare Escentuals
Polycom, Inc.   -> Polycom

I have found the following threads that seem similar to this question, but the poster has not approved and I'm not sure if their use-case is applicable:

How to find best fuzzy match for a string in a large string database

Matching inexact company names in Java

Solution

You can start with using SOUNDEX(), this will probably do for what you need (I picture an auto-suggestion box of already-existing alternatives for what the user is typing).

The drawbacks of SOUNDEX() are:

its inability to differentiate longer strings. Only the first few characters are taken into account, longer strings that diverge at the end generate the same SOUNDEX value
the fact the the first letter must be the same or you won't find a match easily. SQL Server has DIFFERENCE() function to tell you how much two SOUNDEX values are apart, but I think MySQL has nothing of that kind built in.
for MySQL, at least according to the docs, SOUNDEX is broken for unicode input

Example:

SELECT SOUNDEX('Microsoft')
SELECT SOUNDEX('Microsift')
SELECT SOUNDEX('Microsift Corporation')
SELECT SOUNDEX('Microsift Subsidary')

/* all of these return 'M262' */

For more advanced needs, I think you need to look at the Levenshtein distance (also called "edit distance") of two strings and work with a threshold. This is the more complex (=slower) solution, but it allows for greater flexibility.

Main drawback is, that you need both strings to calculate the distance between them. With SOUNDEX you can store a pre-calculated SOUNDEX in your table and compare/sort/group/filter on that. With the Levenshtein distance, you might find that the difference between "Microsoft" and "Nzcrosoft" is only 2, but it will take a lot more time to come to that result.

In any case, an example Levenshtein distance function for MySQL can be found at codejanitor.com: Levenshtein Distance as a MySQL Stored Function (Feb. 10th, 2007).