Fetch row with pdo and relational database

问题

i have a little problem, i have a database with 2 tables, users and comments and i need to print the result with pdo. if i try this code, everything works great:

$stmt = $dbConnection->prepare("SELECT comment_text, username FROM users, comments WHERE users.user_id = comments.user_id");
$stmt->execute();
$stmt->fetch(PDO::FETCH_ASSOC);

foreach ($stmt as $row) {
    echo $row['comment_text'] . "<br>By " . $row['username'] . "<br>";
}

But if i try to add a variable which get the result of fetch i get a totally different result with only 2 rows and only the first letter of the value...

$stmt = $dbConnection->prepare("SELECT comment_text, username FROM users, comments WHERE users.user_id = comments.user_id");
$stmt->execute();
$comment = $stmt->fetch(PDO::FETCH_ASSOC);

foreach ($comment as $row) {
    echo $row['comment_text'] . "<br>By " . $row['username'] . "<br>";
}

回答1:

if i try this code, everything works great:

it is not.
this way you are losing the very first comment. So it should be just

$stmt->execute();
foreach($stmt as $row )
{
    echo $row['comment_text']."<br>By ".$row['username']."<br>" ;
}

in case you want to save the result in array, you have to use the appropriate function for that:

$stmt->execute();
$comments = $stmt->fetchAll(PDO::FETCH_ASSOC);
foreach($comments as $row )
{
    echo $row['comment_text']."<br>By ".$row['username']."<br>" ;
}

while fetch() is getting you only one record, fetchAll() is doing what the name suggests

回答2:

Both your samples aren't functionning properly :

In the first one you loop over every row except the first row, for which you did a fetch, and then did nothing with this first row.

In the second one you loop over every field of the first row, which produce some unexepected output.

来源：https://stackoverflow.com/questions/39292919/fetch-row-with-pdo-and-relational-database

标签

php

mysql

pdo