Question

当我在PHPmyadmin中运行此查询SELECT COUNT(ID) FROM blog_posts时，它会返回我想要的数据库中的行数，但现在我希望使用{{success.php页面显示此数字。 1}}下面。

到目前为止，我的代码是： count method

Database.class.php

<?php include 'config/config.php'; // Inlude the config file, this is where the database login info is stored in an array class database { private $dbc; // Define a variable for the database connection, it's visabiliatly is set to 'private' so only this class can access it function __construct($dbConnection){ // Running the __construct() magic function, // I am passing through a variable into the contruct method which when the object is created will hold the login details from the $dsn array in config.php $this->dbc = $dbConnection; // This is saying that the variable $dbc now has the same value as $dbConnection ($dsn array) $this->dbc = mysqli_connect($this->dbc['host'], $this->dbc['username'], $this->dbc['password'], $this->dbc['database']); // ^ Running the mysqli_connect function to connect to the database. if(mysqli_connect_errno()){ // If there is a problem connecting it will throw and error die("Database connection failed" . mysqli_connect_error()); } else { echo "allgood"; } } function insert($insertSQL){ // Creating an insert function and passing the $insertSQL variable into it mysqli_query($this->dbc, $insertSQL); // Querying the database and running the query that is located in 'success.php'. if (mysqli_connect_errno($this->dbc)) { // Will throw an error if there is a problem die("Failed query: $insertSQL" . $this->dbc->error); } } function count($countSQL){ // This is the method used for counting mysqli_query($this->dbc, $countSQL); if (mysqli_connect_errno($this->dbc)) { // Will throw an error if there is a problem die("Failed query: $countSQL" . $this->dbc->error); } } } ?>

Success.php

Answer 1

实际上，在查询中添加别名要好得多：

$countSQL = "SELECT COUNT(ID) as total FROM blog_posts";
$result = $objdb->count($countSQL);
echo $result['total'];

然后，在你的方法上：

function count($countSQL){ // This is the method used for counting
    $query = mysqli_query($this->dbc, $countSQL);

    if (mysqli_connect_errno($this->dbc)) { // Will throw an error if there is a problem
        die("Failed query: $countSQL" . $this->dbc->error);
    }

    $result = $query->fetch_assoc();
    return $result;
}

其他信息：

在其他方法上放置返回值可能也不错。这样你就会知道它运作正常。

示例：

function insert($insertSQL){ // Creating an insert function and passing the $insertSQL variable into it

    $query = mysqli_query($this->dbc, $insertSQL); // Querying the database and running the query that is located in 'success.php'.

    if (mysqli_connect_errno($this->dbc)) { // Will throw an error if there is a problem
        die("Failed query: $insertSQL" . $this->dbc->error);
    }

    return $this->dbc->affected_rows;

}

所以在这里：

$insertSQL = "INSERT INTO blog_posts VALUES(NULL, 'Test', 'THis is a message')";
$insert = $objdb->insert($insertSQL); // so that its easy to test if it indeed inserted
if($insert > 0) {
    // hooray! inserted!
}

如何使用SQL查询COUNT显示行数

1 个答案: