MySQL find_in_set 与多个搜索字符串

Question

I find that find_in_set only search by a single string:-

find_in_set('a', 'a,b,c,d')

In the above example, 'a' is the only string used for search.

Is there any way to use find_in_set kind of functionality and search by multiple strings, like:-

find_in_set('a,b,c', 'a,b,c,d')

In the above example, I want to search by three strings 'a,b,c'.

One way I see is using OR

find_in_set('a', 'a,b,c,d') OR find_in_set('b', 'a,b,c,d') OR find_in_set('b', 'a,b,c,d')

Is there any other way than this?

Answer 1

没有本机功能可以做到这一点，但您可以使用以下技巧实现您的目标

WHERE CONCAT(",", `setcolumn`, ",") REGEXP ",(val1|val2|val3),"

Answer 2

The MySQL function find_in_set() can search only for one string in a set of strings.

The first argument is a string, so there is no way to make it parse your comma separated string into strings (you can't use commas in SET elements at all!). The second argument is a SET, which in turn is represented by a comma separated string hence your wish to find_in_set('a,b,c', 'a,b,c,d') which works fine, but it surely can't find a string 'a,b,c' in any SET by definition - it contains commas.

Answer 3

You can also use this custom function

CREATE FUNCTION SPLIT_STR(
  x VARCHAR(255),
  delim VARCHAR(12),
  pos INT
)
RETURNS VARCHAR(255)
RETURN REPLACE(SUBSTRING(SUBSTRING_INDEX(x, delim, pos),
       LENGTH(SUBSTRING_INDEX(x, delim, pos -1)) + 1),
       delim, ''); 

DELIMITER $$
    CREATE FUNCTION `FIND_SET_EQUALS`(`s1` VARCHAR(200), `s2`  VARCHAR(200)) 
    RETURNS TINYINT(1)
    LANGUAGE SQL
    BEGIN
          DECLARE a INT Default 0 ;
            DECLARE isEquals TINYINT(1) Default 0 ;
          DECLARE str VARCHAR(255);
          IF s1 IS NOT NULL AND s2 IS NOT NULL THEN
             simple_loop: LOOP
                 SET a=a+1;
                 SET str= SPLIT_STR(s2,",",a);
                 IF str='' THEN
                    LEAVE simple_loop;
                 END IF;
                 #Do  check is in set
                 IF FIND_IN_SET(str, s1)=0 THEN
                    SET isEquals=0;
                     LEAVE simple_loop;
                 END IF;
                 SET isEquals=1;
            END LOOP simple_loop;
          END IF;
        RETURN isEquals;
    END;
    $$
    DELIMITER ;

SELECT FIND_SET_EQUALS('a,c,b', 'a,b,c')- 1
SELECT FIND_SET_EQUALS('a,c', 'a,b,c')- 0
SELECT FIND_SET_EQUALS(null, 'a,b,c')- 0

Answer 4

Amazing answer by @Pavel Perminov! - And also nice comment by @doru for dynamically check..

From there what I have made for PHP code CONCAT(',','" . $country_lang_id . "', ',') REGEXP CONCAT(',(', REPLACE(YourColumnName, ',', '|'), '),') this below query may be useful for someone who is looking for ready code for PHP.

$country_lang_id = "1,2";

$sql = "select a.* from tablename a where CONCAT(',','" . $country_lang_id . "', ',') REGEXP CONCAT(',(', REPLACE(a.country_lang_id, ',', '|'), '),') ";

Answer 5

Wow, I'm surprised no one ever mentioned this here.
In a nutshell, If you know the order of your members, then just query in a single bitwise operation.

SELECT * FROM example_table WHERE (example_set & mbits) = mbits;

Explanation:

If we had a set that has members in this order: "HTML", "CSS", "PHP", "JS"... etc.
That's how they're interpreted in MySQL:

"HTML" = 0001 = 1
"CSS"  = 0010 = 2
"PHP"  = 0100 = 4
"JS"   = 1000 = 16

So for example, if you want to query all rows that have "HTML" and "CSS" in their sets, then you'll write

SELECT * FROM example_table WHERE (example_set & 3) = 3;

Because 0011 is 3 which is both 0001 "HTML" and 0010 "CSS" .

Your sets can still be queried using the other methods like REGEXP, LIKE, FIND_IN_SET(), and so on. Use whatever you need.

Answer 6

You can also use the like command for instance:

where setcolumn like '%a,b%'

or

where 'a,b,c,d' like '%b,c%'

which might work in some situations.

Answer 7

您可以使用 in 从两个值中查找匹配值

SELECT * FROM table WHERE  myvals in (a,b,c,d)