Question

I’m wondering how to design my SQL query when I have two separate tables, but should work together…

likes table

Columns – idlikes, idusers, like_what

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user_follow table

Columns – idfollow, follower, following

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What is the best way to design a query for optimization/performance? Can queries be combined? Or am I supposed to separate each query like this:

$iduser = 1 //I am user 1 in database.

$get = $db -> prepare("SELECT * FROM user_follow WHERE follower = ?")
$get -> execute(array($iduser));
while($row = $get->fetch(PDO::FETCH_ASSOC)){
     $following = $row['following']; // get id of user that i'm following

     $likes = $dbh->prepare("SELECT * FROM likes WHERE idusers = ?");
     $likes->execute(array($following));
     // do what I need to..

}

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UPDATE

$following = $dbh->prepare("SELECT L.* FROM likes L JOIN user_follow F on L.iduser = F.iduser_following WHERE F.iduser_follower = ?");
$following->execute(array($iduser));

while($row_following = $following->fetch(PDO::FETCH_ASSOC))
{
  $id1 = $row_following['L.iduser'];
  echo $id1;
}

Answer 1

This will do it in one query

SELECT L.*
FROM likes L
JOIN user_follow F ON L.idusers = F.following
WHERE F.follower = ?

A note on naming: In sql each row contains one value thus column names are typically singular. Thus likes.idusers would typically be likes.iduser

I would also make it clear if it is a FK on iduser, so in the user_follow table I would name follower as iduser_follower and following as isuser_following