mysql concat_ws with the result of a custom function prevents like '%str%' from working

Question

So I have the following sql that works:

SELECT CONCAT_WS('',`brand`,`pattern`,`product_code`,`size`,`normal_price`,`sale_price`,`text_special`,`load_index`,`speed_index`,`id`) `all_columns` FROM baz_tyres
    HAVING (`all_columns`  LIKE '%con%')
    ORDER BY brand asc
    LIMIT 0, 10

This works fine returning any record that contains the search string in any column such as "ContinentalContiCrossContact® LX21549340225/65R17."

But then I also wanted to be able to match just the numerical value from size so I added the custom function I wound here: How to get only Digits from String in mysql?

DELIMITER $$

CREATE FUNCTION `ExtractNumber`(in_string VARCHAR(50)) 
RETURNS INT
NO SQL
BEGIN
    DECLARE ctrNumber VARCHAR(50);
    DECLARE finNumber VARCHAR(50) DEFAULT '';
    DECLARE sChar VARCHAR(1);
    DECLARE inti INTEGER DEFAULT 1;

    IF LENGTH(in_string) > 0 THEN
        WHILE(inti <= LENGTH(in_string)) DO
            SET sChar = SUBSTRING(in_string, inti, 1);
            SET ctrNumber = FIND_IN_SET(sChar, '0,1,2,3,4,5,6,7,8,9'); 
            IF ctrNumber > 0 THEN
                SET finNumber = CONCAT(finNumber, sChar);
            END IF;
            SET inti = inti + 1;
        END WHILE;
        RETURN CAST(finNumber AS UNSIGNED);
    ELSE
        RETURN 0;
    END IF;    
END$$

DELIMITER ;

Now that I have this function I also want to concat the resulting number and use it for the search.

So I added ExtractNumber( size ) into the congat

SELECT CONCAT_WS('',ExtractNumber(`size`),`brand`,`pattern`,`product_code`,`size`,`normal_price`,`sale_price`,`text_special`,`load_index`,`speed_index`,`id`) `all_columns` FROM baz_tyres
HAVING (`all_columns`  LIKE '%con%')
ORDER BY brand asc
LIMIT 0, 10

When the function is involved the like search fails to find any matches. However if I change the havving to a where condition checking for a specific brand name...

SELECT CONCAT_WS('',ExtractNumber(`size`),`brand`,`pattern`,`product_code`,`size`,`normal_price`,`sale_price`,`text_special`,`load_index`,`speed_index`,`id`) `all_columns` FROM baz_tyres
WHERE (`brand`  LIKE '%con%')
ORDER BY brand asc
LIMIT 0, 10

Then I can see that indeed the concat with the function inside does actually work returning "2147483647ContinentalVancoFourSeason 20473361205/7...." but performing a like on this resulting string doesn't match when it should.

Some columns have special chars and I have tried casting the function result to utf8 and it had no effect.

Any ideas why I cant do a like on this concat string?

UPDATE: It's working now.. I had to put the conversion inside the iterator function itself.

RETURN CAST(finNumber AS CHAR);

For some reason convert or cast with the function inside would produce the correct result but still wouldn't allow a like comparison to match afterwards.

So now the following query

SELECT *,CONCAT_WS('',ExtractNumber_CHAR(`size`),`brand`,`pattern`,`product_code`,`size`,`normal_price`,`sale_price`,`text_special`,`load_index`,`speed_index`,`id`) `all_columns` 
FROM `baz_tyres` 
HAVING (`all_columns` LIKE '%nat%' )
ORDER BY `brand`  DESC
LIMIT 0,10

Produces the desired result however a NEW problem has now appeared that is really strange..

If I do the exact same query but order by ASC instead of DESC then I get 0 results.

Really strange that order affects weather any results are returned. If the extract number function is removed ordering either way returns results.

When I put the function back in I can only get results when order by desc.

Can anyone tell me why this odd behavior would occur?

Answer 1

使用 have 子句的语法是这个 SELECT column_name(s) FROM table_name WHERE condition GROUP BY column_name(s) HAVING condition ORDER BY Being 在使用 group by 后与聚合函数一起使用 Try to change query by using group by else use where instead have