mysql计算两个字符串的相似度

一时失言乱红尘 2023-03-03 11:15 12阅读 0赞

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;
    -- max strlen=255
    DECLARE cv0, cv1 VARBINARY(256);
    SET s1_len = CHAR_LENGTH(s1), s2_len = CHAR_LENGTH(s2), cv1 = 0x00, j = 1, i = 1, c = 0;
    IF s1 = s2 THEN
    RETURN 0;
    ELSEIF s1_len = 0 THEN
    RETURN s2_len;
    ELSEIF s2_len = 0 THEN
    RETURN s1_len;
    ELSE
    WHILE j <= s2_len DO
    SET cv1 = CONCAT(cv1, UNHEX(HEX(j))), j = j + 1;
    END WHILE;
    WHILE 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 = 0; ELSE SET cost = 1;
    END IF;
    SET c_temp = CONV(HEX(SUBSTRING(cv1, j, 1)), 16, 10) + cost;
    IF c > c_temp THEN SET c = c_temp; END IF;
    SET c_temp = CONV(HEX(SUBSTRING(cv1, j+1, 1)), 16, 10) + 1;
    IF c > c_temp THEN 
    SET c = c_temp; 
    END IF;
    SET cv0 = CONCAT(cv0, UNHEX(HEX(c))), j = j + 1;
    END WHILE;
    SET cv1 = cv0, i = i + 1;
    END WHILE;
    END IF;
    RETURN c;
    END;
    
    
    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; 
    END IF;
    RETURN ROUND((1 - LEVENSHTEIN(s1, s2) / max_len) * 100);
    END;

测试：

select levenshtein_ratio('abcdef','abc'); -- 50
    select levenshtein_ratio('abcdef','hijklmn'); -- 0
    select levenshtein_ratio('123abcd666','hijk888'); -- 0
    select levenshtein_ratio('123abcd666','hijk6cba'); -- 10
    -- 但对于含中文的字符串，得到的结果并不理想
    select levenshtein_ratio('张三','李四'); -- 67

**参考链接：**

*  [https://www.it1352.com/1658480.html][https_www.it1352.com_1658480.html]
 *  [https://blog.csdn.net/FengHongSeXiaoXiang/article/details/53462187][https_blog.csdn.net_FengHongSeXiaoXiang_article_details_53462187]

[https_www.it1352.com_1658480.html]: https://www.it1352.com/1658480.html
[https_blog.csdn.net_FengHongSeXiaoXiang_article_details_53462187]: https://blog.csdn.net/FengHongSeXiaoXiang/article/details/53462187