I've got a ~300.000 row table including terminology queried using PHP and MySQL + FULLTEXT indexes. However when I searching an incorrect typed term for instance "hyperpext" naturally giving no results.

I have to "compansate" little writing errors and becoming nearest record from database. The Way I can accomplish such feaure? I understand (really, learned today) about Levenshtein distance, Soundex and Metaphone calculations but presently not getting a good idea to implement this to querying against database.

Sincerely. (Sorry about my poor British, I am attempting to do my best)

Check this out article based on how you may **implement Levenshtein distance inside a MySQL saved function**.

For offspring, the author's suggestion is to get this done:

```
CREATE FUNCTION LEVENSHTEIN (s1 VARCHAR(255), s2 VARCHAR(255))
RETURNS INT
DETERMINISTIC
BEGIN
DECLARE s1_len, s2_len, i, j, c, c_temp, cost INT
DECLARE s1_char CHAR
DECLARE cv0, cv1 VARBINARY(256)
SET s1_len = CHAR_LENGTH(s1), s2_len = CHAR_LENGTH(s2), cv1 = 0x00, j = 1, i = 1, c =
IF s1 = s2 THEN
RETURN
ELSEIF s1_len = THEN
RETURN s2_len
ELSEIF s2_len = THEN
RETURN s1_len
ELSE
WHILE j <= s2_len DO
SET cv1 = CONCAT(cv1, UNHEX(HEX(j))), j = j + 1
Finish WHILE
As i <= s1_len DO
SET s1_char = SUBSTRING(s1, i, 1), c = i, cv0 = UNHEX(HEX(i)), j = 1
WHILE j <= s2_len DO
SET c = c + 1
IF s1_char = SUBSTRING(s2, j, 1) THEN SET cost = ELSE SET cost = 1 Finish IF
SET c_temp = CONV(HEX(SUBSTRING(cv1, j, 1)), 16, 10) + cost
IF c > c_temp THEN SET c = c_temp Finish IF
SET c_temp = CONV(HEX(SUBSTRING(cv1, j+1, 1)), 16, 10) + 1
IF c > c_temp THEN SET c = c_temp Finish IF
SET cv0 = CONCAT(cv0, UNHEX(HEX(c))), j = j + 1
Finish WHILE
SET cv1 = cv0, i = i + 1
Finish WHILE
Finish IF
RETURN c
Finish
```

Younger crowd offers a LEVENSHTEIN_RATIO assistant method that will evaluate the number of different/total figures, as opposed to a straight edit distance. For example, whether it's 60%, then three-fifths from the figures within the source word aren't the same as the destination word.

```
CREATE FUNCTION LEVENSHTEIN_RATIO (s1 VARCHAR(255), s2 VARCHAR(255))
RETURNS INT
DETERMINISTIC
BEGIN
DECLARE s1_len, s2_len, max_len INT
SET s1_len = LENGTH(s1), s2_len = LENGTH(s2)
IF s1_len > s2_len THEN SET max_len = s1_len ELSE SET max_len = s2_len Finish IF
RETURN ROUND((1 - LEVENSHTEIN(s1, s2) / max_len) * 100)
Finish
```

In the comments of http://dev.mysql.com/doc/refman/5./en/udf-producing.html

now i download the package in the mysql udf repository http://empyrean.lib.ndsu.nodak.edu/~nem/mysql/

```
wget http://empyrean.lib.ndsu.nodak.edu/~nem/mysql/udf/dludf.cgi?ckey=28
ll
tar -xzvf dludf.cgi?ckey=28
gcc -shared -o libmysqllevenshtein.so mysqllevenshtein.cc -I/usr/include/mysql/
mv libmysqllevenshtein.so /usr/lib
mysql -uroot -pPASS
mysql> use DATABASE
mysql> CREATE FUNCTION levenshtein RETURNS INT SONAME 'libmysqllevenshtein.so'
mysql> choose levenshtein(w1.word,w2.word) as dist from word w1, word w2 where ETC........... order by dist asc limit ,10
```

I would recommend that you simply generate typo versions around the query input.

i.e. hyperpext > etc

One of these simple is certain to function as the correct spelling (specifically for common misspellings)

How you identify probably the most likely match would be to perform a research for every with an index which informs the document frequency from the term. (seem sensible?)