[SOLVED] Find multiple ids stored in a string in Mysql

Find multiple ids stored in a string in Mysql

I have a string that looks like this: pi_18944000_780345308_54210001000_345900_text

How do I extract all the Ids located in it and store it?

I tried something like this:


    set @a = (SELECT
      SUBSTRING(SUBSTRING(SUBSTRING('pi_18944000_780345308_54210001000_345900_text',
     (LOCATE('_', 'pi_18944000_780345308_54210001000_345900_text'))), 2), 1, 
    LOCATE('_', SUBSTRING(SUBSTRING('pi_18944000_780345308_54210001000_345900_text',
     (LOCATE('_', 'pi_18944000_780345308_54210001000_345900_text'))), 2)) - 1)
    ); 
    select @a;

set @b = (SELECT
  SUBSTRING(SUBSTRING(SUBSTRING(SUBSTRING(SUBSTRING(
  'pi_18944000_780345308_54210001000_345900_text'  , (  LOCATE('_',  'pi_18944000_780345308_54210001000_345900_text'  ))  ), 2),
  LOCATE('_', SUBSTRING(SUBSTRING(  'pi_18944000_780345308_54210001000_345900_text',  (  LOCATE('_', 'pi_18944000_780345308_54210001000_345900_text'
  ))), 2))), 2), 1, LOCATE('_', SUBSTRING(SUBSTRING(SUBSTRING(SUBSTRING(  'pi_18944000_780345308_54210001000_345900_text'  , (
  LOCATE(  '_',  'pi_18944000_780345308_54210001000_345900_text'  ))), 2),
  LOCATE('_',  SUBSTRING(SUBSTRING(  'pi_18944000_780345308_54210001000_345900_text',  (
  LOCATE('_',  'pi_18944000_780345308_54210001000_345900_text'  )))  , 2))), 2)) - 1) );

select @b;

This works but its really complex. Just wanted to see if there is a better way to do this?

Solution

Here's a somewhat simpler solution. It uses the SUBSTRING_INDEX() built-in function. It only requires referencing the string expression once.

mysql> set @str = 'pi_18944000_780345308_54210001000_345900_text';

mysql> SELECT SUBSTRING_INDEX(SUBSTRING_INDEX(@str, '_', 3), '_', -1) AS n;
+-----------+
| n         |
+-----------+
| 780345308 |
+-----------+

See https://dev.mysql.com/doc/refman/8.0/en/string-functions.html#function_substring-index

Next time you should consider not storing multiple id's in a string if you need to reference the individual id's in an SQL expression.