如何创建一个查询而不是两个单独的查询？

Question

I have two queries like this:

$stm = $db->prepare(" SELECT * from table1 where word = :word ");
$stm->bindValue(':word', $word, PDO::PARAM_STR);
$stm->execute();

$iterator = 0;
while ($end = $stm->fetch()) {

    foreach ($db-query(" SELECT * from table2 where id = $end['id']") as $row) {
        echo $row['title'];
    }

    $iterator ++;
}

Now I want to know, is it possible to I write a sub-query instead of that separated query? In other word how can I write those two queries in one query?

Answer 1

The answer to your question is that you can do this in the database. And you should.

A typical response is that you should learn join. However, in this case, in or exists is more appropriate:

select t2.*
from table2 t2
where t2.id in (select id from table1 where word = :word);

I do find it surprising that the condition connecting the two tables is on a column called id in both tables.