如何通过 PHP 中的 PDO 循环遍历 MySQL 查询？
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How do I loop through a MySQL query via PDO in PHP?
提问by Andrew G. Johnson
I'm slowly moving all of my LAMP websitesfrom mysql_functions to PDOfunctions and I've hit my first brick wall. I don't know how to loop through results with a parameter. I am fine with the following:
我正在慢慢地将我的所有功能LAMP websites从mysql_功能转移到PDO功能，并且我已经碰到了我的第一堵砖墙。我不知道如何用参数循环结果。我对以下几点没问题：
foreach ($database->query("SELECT * FROM widgets") as $results)
{
echo $results["widget_name"];
}
However if I want to do something like this:
但是，如果我想做这样的事情：
foreach ($database->query("SELECT * FROM widgets WHERE something='something else'") as $results)
{
echo $results["widget_name"];
}
Obviously the 'something else' will be dynamic.
显然，“别的东西”将是动态的。
回答by Shabbyrobe
Here is an example for using PDO to connect to a DB, to tell it to throw Exceptions instead of php errors (will help with your debugging), and using parameterised statements instead of substituting dynamic values into the query yourself (highly recommended):
这是一个使用 PDO 连接到数据库的示例，告诉它抛出异常而不是 php 错误（将有助于您的调试），并使用参数化语句而不是自己将动态值替换到查询中（强烈推荐）：
// $attrs is optional, this demonstrates using persistent connections,
// the equivalent of mysql_pconnect
$attrs = array(PDO::ATTR_PERSISTENT => true);
// connect to PDO
$pdo = new PDO("mysql:host=localhost;dbname=test", "user", "password", $attrs);
// the following tells PDO we want it to throw Exceptions for every error.
// this is far more useful than the default mode of throwing php errors
$pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
// prepare the statement. the place holders allow PDO to handle substituting
// the values, which also prevents SQL injection
$stmt = $pdo->prepare("SELECT * FROM product WHERE productTypeId=:productTypeId AND brand=:brand");
// bind the parameters
$stmt->bindValue(":productTypeId", 6);
$stmt->bindValue(":brand", "Slurm");
// initialise an array for the results
$products = array();
if ($stmt->execute()) {
while ($row = $stmt->fetch(PDO::FETCH_ASSOC)) {
$products[] = $row;
}
}
// set PDO to null in order to close the connection
$pdo = null;
回答by Darryl Hein
According to the PHP documentationis says you should be able to to do the following:
根据PHP 文档说，您应该能够执行以下操作：
$sql = "SELECT * FROM widgets WHERE something='something else'";
foreach ($database->query($sql) as $results)
{
echo $results["widget_name"];
}
I'm no expert, but this should work.
我不是专家，但这应该有效。
回答by John K
If you like the foreach syntax, you can use the following class:
如果您喜欢 foreach 语法，可以使用以下类：
// Wrap a PDOStatement to iterate through all result rows. Uses a
// local cache to allow rewinding.
class PDOStatementIterator implements Iterator
{
public
$stmt,
$cache,
$next;
public function __construct($stmt)
{
$this->cache = array();
$this->stmt = $stmt;
}
public function rewind()
{
reset($this->cache);
$this->next();
}
public function valid()
{
return (FALSE !== $this->next);
}
public function current()
{
return $this->next[1];
}
public function key()
{
return $this->next[0];
}
public function next()
{
// Try to get the next element in our data cache.
$this->next = each($this->cache);
// Past the end of the data cache
if (FALSE === $this->next)
{
// Fetch the next row of data
$row = $this->stmt->fetch(PDO::FETCH_ASSOC);
// Fetch successful
if ($row)
{
// Add row to data cache
$this->cache[] = $row;
}
$this->next = each($this->cache);
}
}
}
}
Then to use it:
然后使用它：
foreach(new PDOStatementIterator($stmt) as $col => $val)
{
...
}
