mysqli_result::$num_rows()

(PHP 5, PHP 7)

Gets the number of rows in a result

说明

面向对象风格
int $mysqli_result->num_rows;

过程化风格
mysqli_num_rows(mysqli_result$result): int

Returns the number of rows in the result set.

The behaviour of mysqli_num_rows() depends on whether buffered or unbuffered result sets are being used. For unbuffered result sets,mysqli_num_rows() will not return the correct number of rows until all the rows in the result have been retrieved.

参数

$result

仅以过程化样式：由mysqli_query()，mysqli_store_result()或mysqli_use_result()返回的结果集标识。

返回值

Returns number of rows in the result set.

Note:

If the number of rows is greater than PHP_INT_MAX, the number will be returned as a string.

范例

Example #1 面向对象风格

<?php
$mysqli = new mysqli("localhost", "my_user", "my_password", "world");
/* check connection */
if (mysqli_connect_errno()) {
    printf("Connect failed: %s\n", mysqli_connect_error());
    exit();
}
if ($result = $mysqli->query("SELECT Code, Name FROM Country ORDER BY Name")) {
    /* determine number of rows result set */
    $row_cnt = $result->num_rows;
    printf("Result set has %d rows.\n", $row_cnt);
    /* close result set */
    $result->close();
}
/* close connection */
$mysqli->close();
?>

Example #2 过程化风格

<?php
$link = mysqli_connect("localhost", "my_user", "my_password", "world");
/* check connection */
if (mysqli_connect_errno()) {
    printf("Connect failed: %s\n", mysqli_connect_error());
    exit();
}
if ($result = mysqli_query($link, "SELECT Code, Name FROM Country ORDER BY Name")) {
    /* determine number of rows result set */
    $row_cnt = mysqli_num_rows($result);
    printf("Result set has %d rows.\n", $row_cnt);
    /* close result set */
    mysqli_free_result($result);
}
/* close connection */
mysqli_close($link);
?>

以上例程会输出：

Result set has 239 rows.

参见

• mysqli_affected_rows() Gets the number of affected rows in a previous MySQL operation
• mysqli_store_result() 转移上一次查询返回的结果集
• mysqli_use_result() Initiate a result set retrieval
• mysqli_query() 对数据库执行一次查询

If you have problems making work this num_rows, you have to declare ->store_result() first.
<?php
$mysqli = new mysqli("localhost","root", "", "tables");
$query = $mysqli->prepare("SELECT * FROM table1");
$query->execute();
$query->store_result();
$rows = $query->num_rows;
echo $rows;
// Return 4 for example
?>

The method signature should be:
mixed mysqli_num_rows (mysqli_result $result)
"If the number of rows is greater than PHP_INT_MAX, the number will be returned as a string."

This function doesn't work with LIMIT used jointly with SQL_CALC_FOUND_ROWS. If you want to obtain the total rows found you must do it manually, example:
<?php
public function errorList(int $limit=25,int $offset=0){
    $errorList = array();
    $result = $this->con->query("SELECT SQL_CALC_FOUND_ROWS id, erreur FROM Erreurs ORDER BY id DESC LIMIT $limit OFFSET $offset");
    while($row = $result->fetch_assoc()){
      $errorList[] = new Erreur($row);
    }
    $result->free();
    // $foundRows = $result->num_rows; // 25
    $foundRows = $this->con->query("SELECT FOUND_ROWS() as foundRows"); 
    $this->foundRows = $foundRows->fetch_assoc(); // 178
    return $errorList;
}
?>

in php 5.3.8 had unexpected troubles when checking for mysqli_result::$num_rows
If the result of the query is empty then var_dump of the result will be like this:
class mysqli_result#5 (5) {
 public $current_field => NULL
 public $field_count => NULL
 public $lengths => NULL
 public $num_rows => NULL
 public $type => NULL
}
but var_dump($result->num_rows) will give integer-typed zero instead of NULL:
int(0)

// Create Database Connection ..
$conn = new mysqli("localhost", "root", "", "my_db");
// run a query on a table from your DB.
$sql_rec = $conn->query("select count(msisdn) from my_colum where id = '$id'"); // Take out the Where Clause if not Needed.
      if($sql_rec == true)
    {
     echo " The Total Number of MSISDNs are " . $sql_rec->num_rows;  
    }
     else
    {
     echo "Something Bad has happened, We have informed the village Elders.". $conn->connect_error();
    }
$conn->close();