从php中的mysql表中选择count(*)

Question

我能够获取 mysql 查询结果的值和行。

但我正在努力获取查询的单个输出。例如：

$result = mysql_query("SELECT COUNT(*) FROM Students;");

我需要显示结果。但我没有得到结果。

我尝试过以下方法：

1. mysql_fetch_assoc()
2. mysql_free_result()
3. mysql_fetch_row()

但我没有成功显示（获取）实际值。

Answer 1

您需要使用 as 关键字为聚合别名，以便从 mysql_fetch_assoc 调用它

$result=mysql_query("SELECT count(*) as total from Students");
$data=mysql_fetch_assoc($result);
echo $data['total'];

Answer 2

如果您只需要该值：

$result = mysql_query("SELECT count(*) from Students;");
echo mysql_result($result, 0);

Answer 3

$result = mysql_query("SELECT COUNT(*) AS `count` FROM `Students`");
$row = mysql_fetch_assoc($result);
$count = $row['count'];

试试这个代码。

Answer 4

请开始使用 PDO。

mysql_* 从 PHP 5.5.0 开始已弃用，并将在 7 中完全删除。让我们更轻松地升级并立即开始使用它。

$dbh = new \PDO($dsn, $user, $password);
$sth = $dbh->prepare('SELECT count(*) as total from Students');
$sth->execute();
print_r($sth->fetchColumn());

Answer 5

这是使用 PHP 显示表中行数的代码

$sql="select count(*) as total from student_table";
$result=mysqli_query($con,$sql);
$data=mysqli_fetch_assoc($result);
echo $data['total'];

Answer 6

$num_result = mysql_query("SELECT count(*) as total_count from Students ") or exit(mysql_error());
$row = mysql_fetch_object($num_result);
echo $row->total_count;

Answer 7

您也可以使用它并升级到 mysqli_ （停止使用 mysql_* 扩展...）

$result = mysqli_query($conn, "SELECT COUNT(*) AS `count` FROM `Students`");
$row = mysqli_fetch_array($result);
$count = $row['count'];
echo $count;

Answer 8

使用 mysql v5.7.20，以下是我如何使用 PHP v7.0.22 从表中获取行计数：

$query = "select count(*) from bigtable";
$qresult = mysqli_query($this->conn, $query);
$row = mysqli_fetch_assoc($qresult);
$count = $row["count(*)"];
echo $count;

第三行将返回如下所示的结构：

array(1) {
   ["count(*)"]=>string(4) "1570"
}

在这种情况下，结束 echo 语句将返回：

1570

Answer 9

对于 mysqli 用户，代码将如下所示：

$mysqli = new mysqli($db_host, $db_user, $db_pass, $db_name);

$result = $mysqli->query("SELECT COUNT(*) AS Students_count FROM Students")->fetch_array();
var_dump($result['Students_count']);

或：

$mysqli = new mysqli($db_host, $db_user, $db_pass, $db_name);

$result = $mysqli->query("SELECT COUNT(*) FROM Students")->fetch_array();
var_dump($result[0]);

Answer 10

$db  = new PDO('mysql:host=localhost;dbname=java_db', 'root', 'pass');
$Sql = "SELECT count(*) as `total` FROM users";
$stmt = $db->query($Sql);
$stmt->execute();
$total = $stmt->fetch(PDO::FETCH_ASSOC);
print '<pre>';
print_r($total);
print '</pre>';

结果：

Answer 11

您需要使用 as 关键字为聚合别名，以便从 mysqli_fetch_assoc 调用它

$result=mysqli_query($conn,"SELECT count(*) as total from Students");
$data=mysqli_fetch_assoc($result);
echo $data['total'];

Answer 12

 $howmanyuser_query=$conn->query('SELECT COUNT(uno)  FROM userentry;');
 $howmanyuser=$howmanyuser_query->fetch_array(MYSQLI_NUM); 
 echo $howmanyuser[0];

经过这么多个小时的努力，非常棒:)