PHP Pdo - Num Rows

Row count with PDO

$sql = "SELECT count(*) FROM `table` WHERE foo = ?"; 
$result = $con->prepare($sql); 
$result->execute([$bar]); 
$number_of_rows = $result->fetchColumn(); 

Not the most elegant way to do it, plus it involves an extra query.

PDO has PDOStatement::rowCount(), which apparently does not work in MySql. What a pain.

From the PDO Doc:

For most databases,
PDOStatement::rowCount() does not
return the number of rows affected by
a SELECT statement. Instead, 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.

EDIT: The above code example uses a prepared statement, which is in many cases is probably unnecessary for the purpose of counting rows, so:

$nRows = $pdo->query('select count(*) from blah')->fetchColumn(); 
echo $nRows;

PHP PDO - Num Rows

According to the manual, there is a PDOStatement->rowCount method ; but it shouldn't be used (quoting) :

For most databases,
PDOStatement::rowCount() does not
return the number of rows affected by
a SELECT statement.
Instead, 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.

If you already have a recordset, and want to know how many lines are in it, you'll have to fetch the data, using one of the fetch* methods ; and use count -- like you suggested.

Alternative for mysql_num_rows using PDO

$res = $DB->query('SELECT COUNT(*) FROM table');
$num_rows = $res->fetchColumn();

or

$res = $DB->prepare('SELECT COUNT(*) FROM table');
$res->execute();
$num_rows = $res->fetchColumn();

You can use this to ask if data exists or is selected, too:

$res = $DB->query('SELECT COUNT(*) FROM table');
$data_exists = ($res->fetchColumn() > 0) ? true : false;

Or with your variables:

$res = $DB->query('SELECT COUNT(*) FROM table');
$message = ($res->fetchColumn() > 0) ? array('status' => 'ok') : array('status' => 'error');

How do I count unique rows in php pdo?

You can use distinct in mysql to select only unique fields in your table.

$query = "SELECT distinct user_id FROM users";
$stmt = $db->prepare($query);
$stmt->execute();
$count = $stmt->rowCount();

How to count number of rows in MySQL table (PHP PDO)

you are overriding the $stmt after execute using fetchAll()

so instead try this

$stmt->execute();
 $totalrows = $stmt->rowCount(); 
 echo $totalrows;
 // Pick up the result as an array
 $result = $stmt->fetchAll();

how to get the count of row values in php pdo

In Mysql $stmt->rowCount(); doesnt work. Try this

$nRows = $pdo->query('select count(*) from yourTable')->fetchColumn(); 
echo 'Number of rows is = '. $nRows;

Here is an excerpt from a comment and answer regarding the same. Check it out its very resourceful.

mysql_num_rows() worked is because it was internally fetching all the rows to give you that information, even if it didn't seem like it to you. Refer to this anwere

So in PDO, your options are:

1. Use MySQL's FOUND_ROWS() function.
2. Use PDO's fetch_all() function to fetch all the rows into an array,
   then use count() on it.
3. Do an extra query to SELECT COUNT(*),

https://stackoverflow.com/a/883523/2536812

PDO::rowCount VS COUNT(*)

1st question:

Using count COUNT(), internally the server(MySQL) will process the request differently.

When doing COUNT(), the server(MySQL) will only allocate memory to store the result of the count.

When using $row=$SQL->rowCount(); the server (Apache/PHP) will process the entire result set, allocate memory for all those results, and put the server in fetching mode, which involves a lot of different details, such as locking.

Take note that PDOStatement::rowCount() returns the number of rows affected by the last statement, not the number of rows returned. If the last SQL statement executed by the associated PDOStatement was a SELECT statement, some databases may return the number of rows returned by that statement. However, this behaviour is not guaranteed for all databases and should not be relied on for portable applications.

On my analysis, if you use COUNT(), the process would be divided to both MySQL and PHP while if you use $row=$SQL->rowCount();, the processing would be more for PHP.

Therefore COUNT() in MySQL is faster.

2nd question:

COUNT(*) is better than COUNT(id).

Explanation:

The count(*) function in mysql is optimized to find the count of values. Using wildcard means it does not fetch every row. It only find the count. So use count(*) wherever possible.

Sources:

• PDOStatement::rowCount
• MySQL COUNT(*)

How to count the number of rows in MySQL using PHP PDO

If you have a PDO Object with a PDO connection to your database -
(Let´s call it for example $con)
You can prepare a statement like

     $stmt = $con->prepare('SELECT movie_name FROM movie_info LIMIT 3 OFFSET 0');

     // Then fire it up
     $stmt->execute();

     // Pick up the result as an array
     $result = $stmt->fetchAll();

     // Now you run through this array in many ways, for example
     for($x=0, $n=count($result); $x < $n; $x++){
         echo $result[$x]['movie_name'];
     } 

The count($result) keeps your number of result

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