Select comma-separated records from table

Question

Table : frei_session

id  username        accountId   status  status_mesg

14  Sumit Bijvani   50          0       I am available
16  Dilip Borad     49          1       I am available
15  Karan Bijvani   51          1       I am available

Table : users

accountId    friends

49           50,52
50           49,52,51,44
51           50

I have 2 tables, frei_session have records of online users and users table have data of users and friends of them separated ID by comma.

I want to retrieve data from frei_session table based on friends column of users table.

For Ex

If user 49 is online, I want Output like below

id  username        accountId   status  status_mesg

14  Sumit Bijvani   50          0       I am available

Because User 50 and 52 is friend of User 49 but now only User 50 is online

I have tried following query on single table but don't know how to do with 2 tables

SELECT DISTINCT status_mesg,username,session_id,status,guest
    FROM frei_session
    WHERE accountId!=49
    AND guest=0
    AND status!=2
    AND status!=0

Answer 1

Your table is not normalize an considered as bad schema design. Anyway, to answer your question directly, MySQL has a builtin function called FIND_IN_SET which searches for a specific value on a CSV format.

SELECT  b.*
FROM    users a
        INNER JOIN frei_session b
            ON FIND_IN_SET(b.accountID, a.friends) > 0
WHERE   b.status = 0 AND
        a.accountID = 49

• SQLFiddle Demo