Get Number of Rows Matched by Update Query with PHP MySQLi

Get number of rows matched by UPDATE query with PHP mysqli

it's in the options of mysqli_real_connect.

Also introduced in PDO::MySQL in PHP 5.3.

PHP, MySQL - can you distinguish between rows matched and rows affected?

From the MySQL documentation for mysql_affected_rows:

For UPDATE statements, if you specify
the CLIENT_FOUND_ROWS flag when
connecting to mysqld,
mysql_affected_rows() returns the
number of rows matched by the WHERE
clause. Otherwise, the default
behavior is to return the number of
rows actually changed.

With mysqli, you can specify the CLIENT_FOUND_ROWS using mysqli::real_connect.

$db = mysqli_init();
$db->real_connect('host', 'username', 'password', 'dbname', '3306', null, MYSQLI_CLIENT_FOUND_ROWS);

In PDO, the constant is named PDO::MYSQL_ATTR_FOUND_ROWS

$db = new PDO('mysql:dbname=mydatabase;host=myhost', 'username', 'password', array(
    PDO::MYSQL_ATTR_FOUND_ROWS => true
));

With the old and deprecated MySQL extension, you can specify the CLIENT_FOUND_ROWS passing the value 2 as the 5th parameter for mysql_connect (source).

How can I count the numbers of rows that a MySQL query returned?

Getting total rows in a query result...

You could just iterate the result and count them. You don't say what language or client library you are using, but the API does provide a mysql_num_rows function which can tell you the number of rows in a result.

This is exposed in PHP, for example, as the mysqli_num_rows function. As you've edited the question to mention you're using PHP, here's a simple example using mysqli functions:

$link = mysqli_connect("localhost", "user", "password", "database");

$result = mysqli_query($link, "SELECT * FROM table1");
$num_rows = mysqli_num_rows($result);

echo "$num_rows Rows\n";

Getting a count of rows matching some criteria...

Just use COUNT(*) - see Counting Rows in the MySQL manual. For example:

SELECT COUNT(*) FROM foo WHERE bar= 'value';

Get total rows when LIMIT is used...

If you'd used a LIMIT clause but want to know how many rows you'd get without it, use SQL_CALC_FOUND_ROWS in your query, followed by SELECT FOUND_ROWS();

SELECT SQL_CALC_FOUND_ROWS * FROM foo
   WHERE bar="value" 
   LIMIT 10;

SELECT FOUND_ROWS();

For very large tables, this isn't going to be particularly efficient, and you're better off running a simpler query to obtain a count and caching it before running your queries to get pages of data.

The update query is successful but num_rows returns error

I think you are trying to get the number of records get affected. mysql_affected_rows returns the number of rows affected by the last INSERT, UPDATE, REPLACE or DELETE query.

To check the affected rows use

$sql = "UPDATE `tbl_override_marks` SET final_mark ='$mark', confirmed ='Y' 
    WHERE fk_class_sub_id ='$cls_sub'";
$result = $conn->query($sql);
echo $conn->affected_rows;

You can check the manual mysqli::$affected_rows

mysqli-query returns true on update, but no rows affected

Okay, so I found the problem.

I was starting a transaction within a method, and I never comitted.

My apologies for wasting your time, you could not have figured out the problem by looking at the code I provided. I was sure the issue was within that query method (but I was wrong).

I'll vote up each and everyone of you that tried to help out.

---

Related Topics