Prepared Statements - Number of Rows

Question

I\'m learning about prepared statements and trying to work with a query that yields multiple rows of results. Right now, I\'m just trying to figure out how to determine the

Answer 1

This works as of Feb 2020:

$number_of_records = $stmt->rowCount();
echo $number_of_records;

From php.net manual:

PDOStatement::rowCount() returns the number of rows affected by a DELETE, INSERT, or UPDATE statement.

Here is an example from their website:

<?php
/* Delete all rows from the FRUIT table */
$del = $dbh->prepare('DELETE FROM fruit');
$del->execute();

/* Return number of rows that were deleted */
print("Return number of rows that were deleted:\n");
$count = $del->rowCount();
print("Deleted $count rows.\n");
?>

The above example will output:

Return number of rows that were deleted:
Deleted 9 rows.

Answer 2

If you are only interested in the row count instead of the actual rows of data, here is a complete query block with a COUNT(*) call in the SELECT clause.

$conn = new mysqli("host", "user", "pass", "db");
$stmt = $conn->prepare("SELECT COUNT(*) FROM `table` WHERE id= ?");
$stmt->bind_param("s", $id);
$stmt->execute()
$stmt->bind_result($num_rows)
$stmt->fetch()
$num_rows;

Or if you want to know the row count before iterating/processing the rows, one way is to lump the entire resultset (multi-dimensional array) into a variable and call count() before iterating.

$conn = new mysqli("host", "user", "pass", "db");
$sql = "SELECT field1, field2, field3
        FROM table
        WHERE id= ?
        ORDER BY id";
$stmt = $conn->prepare($sql);
$stmt->bind_param("s", $id);
$stmt->execute();
$result = $stmt->get_result();
$resultset = $result->fetch_all(MYSQLI_ASSOC);
echo "<div>Num: " , count($resultset) , "</div>";
foreach ($resultset as $row) {
    echo "<div>Row: {$row['field1']} & {$row['field2']} & {$row['field3']}</div>";
}

*I have tested both of the above snippets to be successful on my localhost.

Answer 3

num_rows returns the number, you have to store it in a variable.

/*.....other code...*/
$numberofrows = $stmt->num_rows;
/*.....other code...*/

echo '# rows: '.$numberofrows;

So full code should be something like this:

if($stmt = $mysqli -> prepare("SELECT field1, field2, field3 FROM table WHERE id= ? ORDER BY id ASC")) 
    {
    /* Bind parameters, s - string, b - blob, i - int, etc */
    $stmt -> bind_param("i", $id);
    $stmt -> execute();

    /* Bind results */
    $stmt -> bind_result($testfield1, $testfield2, $testfield3);

    /* Fetch the value */
    $stmt -> fetch();
    $numberofrows = $stmt->num_rows;

    /* Close statement */
    $stmt -> close();
   }
echo '# rows: '.$numberofrows;

Answer 4

Check out the example #2 here: PHP.net

Use PDO::query() to issue a SELECT COUNT(*) statement with the same predicates as your intended SELECT statement, then use PDOStatement::fetchColumn() to retrieve the number of rows that will be returned. Your application can then perform the correct action.