如何将字符串与另一个几乎相同的字符串匹配（模糊匹配）

Question

In Rails, I am passing in a string: 'AE18BX21'. I am querying the database to find strings that match with the input string. However the input string and the string in the database sometimes don't match up. Sometimes there is an extra letter/number, sometimes a letter/number is missing, or sometimes the letter/number is a different letter/number.

I have tried a few different regex expressions like:

Table.where("string =~ ?", 'A+E+1+8+B+X+2+1')

Table.where("string =~ ?", '(A|.)+(E|.)+(1|.)+(8|.)+(B|.)+(X|.)+(2|.)+(1|.)')

In an ideal world, I would want it to return only the strings that match up 80% or more.

Answer 1

After reading your question, I think you want something like Levenshtein distance, and as you stated in your comment, for Postgres you could use it.

Quoting its documentation here: https://www.postgresql.org/docs/9.1/static/fuzzystrmatch.html

test=# SELECT levenshtein('GUMBO', 'GAMBOL');
 levenshtein
-------------
           2
(1 row)

test=# SELECT levenshtein('GUMBO', 'GAMBOL', 2,1,1);
 levenshtein
-------------
           3
(1 row)

test=# SELECT levenshtein_less_equal('extensive', 'exhaustive',2);
 levenshtein_less_equal
------------------------
                      3
(1 row)

test=# SELECT levenshtein_less_equal('extensive', 'exhaustive',4);
 levenshtein_less_equal
------------------------
                      4
(1 row)

Then you can build your sql query with your desire distance:

SELECT * 
FROM YourTable
WHERE levenshtein(string , 'AE18BX21') <= 2