检查PDO prepare（），execute（）是否返回至少一行

Question

Before moving to PDO, I used

$result = mysqli_query ($conn, 'SELECT * FROM mytable WHERE id = 54');
if (mysqli_num_rows($result) >= 1) { ... }

to check if the query returns at least one result.

Now with PDO, I've seen in many SO questions (like get number of rows with pdo) that there is no direct function in PDO to check the number of rows of a query (there are warnings about the use of$result->rowCount();), but rather solutions like doing an extra query:

SELECT count(*) FROM mytable WHERE id = 54

---

But this is maybe too much for what I want : in fact, I don't need the exact number of rows, but just if there is at least one.

How to check if a prepared statement query returns at least one row ?

$stmt = $db->prepare('SELECT * FROM mytable WHERE id = 54');
$stmt.execute();
... // HOW TO CHECK HERE?

Answer 1

$stmt = $db->prepare('SELECT * FROM mytable WHERE id = 54');
$stmt.execute();
... // HOW TO CHECK HERE?

It's so simple, you're almost there already.

$stmt = $db->prepare('SELECT * FROM mytable WHERE id = 54');
$stmt.execute();
$result = $stmt->fetchAll();  // Even fetch() will do
if(count($result)>0)
{
      // at least 1 row
}

And if you just want Yes/No answer then you should also add a LIMIT 1 to your query so mysql doesn't waste trying to look for more rows.