It looks like the table alias names SND and M are confusing you so remove them.
If this is now your tables

TABLE users
userid   firstname    lastname
1         JOHN         DEO
2         JANE         DEO

TABLE msg
msg_id    msg_from     msg_to      received   age  city  country

[download]

The correct SQL (without alias names) is

SELECT users.userid, users.firstname, users.lastname, msg.age, msg.cit
+y, msg.country FROM msg
JOIN users ON users.userid = msg.msg_from
WHERE msg.msg_to = ? 
  AND msg.received IS NULL

[download]
poj

In reply to Re^9: sql join with multiple select by poj
in thread sql join with multiple select by bigup401

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