extracting the ids assigned to a list of user ids

问题

Above question may be confusing so let me explain it. I have a table with structure similar as below :

form_id         bank_ids 

   1            5,6,7,8
   2            7,10
   3            4,7,9
   4            5,8,1

Now suppose I want to extract the form ids assigned to bank_id 7, how can I able to extract it?

回答1:

MySQL has a builtin function for that called FIND_IN_SET.

SELECT *
FROM tableName
WHERE FIND_IN_SET('7', bank_ids) > 0

You should properly normalize your table.

UPDATE

if you want to use LIKE, you need to concatenate , on both side. eg

WHERE CONCAT(',', bank_ids, ',') LIKE CONCAT('%,', '7', ',%')

来源：https://stackoverflow.com/questions/19462626/extracting-the-ids-assigned-to-a-list-of-user-ids