php PDO 从数据库中获取数据
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/13183579/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
PDO get data from database
提问by chizijs
I started using PDO recently, earlier I was using just MySQL. Now I am trying to get all data from database.
我最近开始使用 PDO，之前我只使用 MySQL。现在我试图从数据库中获取所有数据。
$getUsers = $DBH->prepare("SELECT * FROM users ORDER BY id ASC");
$getUsers->fetchAll();
if(count($getUsers) > 0){
while($user = $getUsers->fetch()){
echo $user['username']."<br/>";
}
}else{
error('No users.');
}
But it is not showing any users, just a blank page.
但它没有显示任何用户，只是一个空白页面。
回答by newfurniturey
The PDOmethod fetchAll()returns an array/result-set, which you need to assign to a variable and then use/iterate through that variable:
该PDO方法fetchAll()返回一个数组/结果集，您需要将其分配给一个变量，然后使用/迭代该变量：
$users = $getUsers->fetchAll();
foreach ($users as $user) {
echo $user['username'] . '<br />';
}
UPDATE(missing execute())
Also, it appears you aren't calling the execute()method which needs to happen afteryou prepare the statement but beforeyou actually fetch the data:
UPDATE（失踪execute()）
而且，看来你是不是调用execute()它需要做的方法后，你准备的发言，但之前你真正获取数据：
$getUsers = $DBH->prepare("SELECT * FROM users ORDER BY id ASC");
$getUsers->execute();
$users = $getUsers->fetchAll();
...
回答by Abiola Babatunde
This code below will do what you are asking for:
下面的代码将满足您的要求：
$sql = $dbh->prepare("SELECT * FROM users ORDER BY id ASC");
$sql->execute();
while ($result = $sql->fetch(PDO::FETCH_ASSOC)) {
echo $result['username']."<br/>";
}
回答by Dharman
Your code is missing a call to execute()after prepare(). After your prepared statement is executed you can get the array of records using fetchAll().
您的代码缺少对execute()after的调用prepare()。执行准备好的语句后，您可以使用fetchAll().
$getUsers = $DBH->prepare('SELECT * FROM users ORDER BY id ASC');
$getUsers->execute();
$users = $getUsers->fetchAll();
if ($users) {
foreach ($users as $user) {
echo $user['username']."<br/>";
}
} else {
trigger_error('No users.');
}
However, in you example you are not passing any variable data to the query and you only execute it once, which defeats a purpose of having prepared statement. You should use prepared statements if you need to have variables in your SQL, for example:
但是，在您的示例中，您没有将任何变量数据传递给查询，并且只执行一次，这违背了准备语句的目的。如果您的 SQL 中需要有变量，您应该使用准备好的语句，例如：
$getUsers = $DBH->prepare('SELECT * FROM users WHERE id=?');
$getUsers->execute([
$_GET['user_id']
]);
$user = $getUsers->fetch(); // get single user by unique id
If there are no variables then you can simply use query()method.
如果没有变量，那么您可以简单地使用query()方法。
$users = $DBH->query('SELECT * FROM users ORDER BY id ASC')->fetchAll();
If you do not need to fetch all records at once, you can simply loop on the statement with foreach:
如果您不需要一次获取所有记录，您可以简单地使用以下语句循环foreach：
$getUsers = $DBH->prepare('SELECT * FROM users WHERE username LIKE ? ORDER BY id ASC');
$getUsers->execute([
'%' . $_GET['search'] . '%' // search for username with wildcards
]);
foreach ($getUsers as $user) {
echo $user['username']."<br/>";
}
