How can I implement fuzzy company name matching in MySQL with PHP for auto-completion?

Fuzzy Company Name Matching in MySQL with PHP for Auto-Completion

Introduction

Finding fuzzy matches for company names is a common task in autocomplete systems. This task can be challenging due to the large number of potentially matching companies and the need for efficient search algorithms.

Soundex Indexing

One approach to fuzzy matching is using Soundex indexing. Soundex is a phonetic algorithm that encodes words based on their pronunciation. This allows for approximate matching of words, even if they have different spellings. However, Soundex indexing has limitations, such as being unable to differentiate between longer strings and requiring the first letter to be the same.

Levenshtein Distance

A more advanced approach to fuzzy matching is using the Levenshtein distance. The Levenshtein distance measures the number of insertions, deletions, or substitutions required to transform one string into another. Unlike Soundex, this method does not have the disadvantages mentioned earlier.

Using Levenshtein Distance in PHP

The codejanitor.com website provides an example of a MySQL stored function that calculates the Levenshtein distance. You can use this function to perform fuzzy matching on company names as follows:

// Load MySQL stored function (if not already loaded)
if (!function_exists('Levenshtein')) {
    $sql = "CREATE FUNCTION Levenshtein(s1 VARCHAR(255), s2 VARCHAR(255)) RETURNS INT
    BEGIN
        DECLARE lv_s1, lv_s2 VARCHAR(255);
        DECLARE lv_len1, lv_len2, lv_i, lv_j, lv_c, lv_cost INT;
        DECLARE lv_arr1[255] INT;

        SET lv_s1 = LOWER(s1);
        SET lv_s2 = LOWER(s2);
        SET lv_len1 = LENGTH(lv_s1);
        SET lv_len2 = LENGTH(lv_s2);

        -- Initialize the array
        SET lv_arr1[1] = 0;
        FOR lv_i = 1 TO lv_len1 DO
            SET lv_arr1[lv_i + 1] = lv_i;
        END FOR;

        -- Step 2
        FOR lv_j = 1 TO lv_len2 DO
            SET lv_c = lv_j;
            FOR lv_i = 1 TO lv_len1 DO
                IF SUBSTRING(lv_s1, lv_i, 1) = SUBSTRING(lv_s2, lv_j, 1) THEN
                    SET lv_cost = 0;
                ELSE
                    SET lv_cost = 1;
                END IF;
                SET lv_c = LEAST(lv_c + 1, lv_arr1[lv_i] + lv_cost, lv_arr1[lv_i - 1] + 1);
                SET lv_arr1[lv_i] = lv_c;
            END FOR;
        END FOR;

        RETURN lv_c;
    END;";
    $result = $mysqli->query($sql);
}

// Execute fuzzy matching query
$numWords = 0;
$userInput = "Microsift";
$query = "SELECT company_name, Levenshtein('$userInput', company_name) AS distance
          FROM companies
          ORDER BY distance ASC";
$result = $mysqli->query($query);

// Display results
while ($row = $result->fetch_assoc()) {
    $numWords++;
    echo $row['company_name'] . " (" . $row['distance'] . ")\n";
}

if ($numWords == 0) {
    echo "No matches found.\n";
}

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