I have two tables:
friends:
accountId | friendId
--------------------
A1 | B15
A1 | C34
A1 | D48
and followers
accountId | followerId
----------------------
A1 | B15
A1 | C34
I try to run a MYSQL query that will return a "friendId" that does not exist in "followerId" column in the other table. Basically i try to find, which rows from the "friends" table, do not exist in the "followers" table.
I have tried:
SELECT *
FROM friends AS f
LEFT JOIN followers AS l
ON f.accountId = l.accountId
WHERE l.accountId IS NULL
but it return nothing. No result. Just null. I have checked the validity of the tables manually, and it does actually contain such entries. Any ideas?
You could use:
SELECT *
FROM friends AS f
LEFT JOIN followers AS l
ON f.accountId = l.accountId
AND f.friend_id = l.follower_id -- additional condition
WHERE l.accountId IS NULL;
Output:
accountId | friendId | accountId | follower_id
A1 | D48 | NULL | NULL
Collected from the Internet
Please contact [email protected] to delete if infringement.
Comments