Question

我对这段代码很困惑。由于我是PDO的新手，因此我需要一些帮助来全面了解以下内容。它已成功在MySQL中创建数据库，但未在表中创建数据库。我不知道这段代码有什么问题。请有人帮忙。

该错误显示为：

数据库创建成功

创建数据库产品

SQLSTATE [3D000]：无效的目录名称：1046未选择数据库

$host    = "localhost";
$user    = "root";
$pass    = "";

try{
    $sql     =  "CREATE DATABASE products";

    $pdo     = new PDO('mysql:host=$host', $user, $pass);
    $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    $pdo->exec($sql);
    echo "Database created successfully";


    $create_products = "CREATE TABLE  products (
            id INT(6) AUTO_INCREMENT NOT NULL,
            type VARCHAR(10) NOT NULL,
            firstname VARCHAR(40) NOT NULL,
            mainname VARCHAR(40) NOT NULL,
            title VARCHAR(50) NOT NULL,
            price INT (10) NOT NULL,
            numpages int(5) NOT NULL,
            playlength int(10) NOT NULL,
            discount int(10) NOT NULL,
            PRIMARY KEY (`id`))";
    $pdo->query($create_products);

    $pdo->query("INSERT INTO products 
                            (type, firstname, mainname, title, price, numpages, playlength, discount) 
                    values ('book', 'willa', 'cather', 'my antonia', 4.22, 200, NULL, 0 )");

    $pdo->query( "INSERT INTO products 
                            ( type, firstname, mainname, title, price, numpages, playlength, discount) 
                    values ('cd', 'the', 'clash', 'london calling', 4.22, 200, 60, 0 )");

    $pdo->query( "INSERT INTO products 
                            (type, firstname, mainname, title, price, numpages, playlength, discount) 
                    values ('shop', NULL, 'pears', 'soap', 4.22, NULL, NULL, 0 )");

    $pdo->query( "INSERT INTO products 
                            (type, firstname, mainname, title, price, numpages, playlength, discount) 
                    values ('book', NULL, 'johnson', 'shampoo', 4.22, 200, NULL, 0 )");

}
catch (PDOException $e) {
    echo $sql . "<br>" . $e->getMessage();
}

Answer 1

创建数据库后使用它，以便PDO知道它正在使用哪个数据库。

$pdo     = new PDO('mysql:host=$host', $user, $pass);
$pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$pdo->exec($sql);
echo "Database created successfully";
$pdo->exec('USE products');  // <<---- add this to your code

Answer 2

通常，在打开PDO连接时，您指定要连接的数据库。当然，在创建数据库时，您不能这样做。

因此，请关闭连接，然后使用指定的新数据库重新打开

$host    = "localhost";
$user    = "root";
$pass    = "";

try{
    $pdo = new PDO('mysql:host=$host', $user, $pass);
    $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

    $sql = "CREATE DATABASE products";
    $pdo->exec($sql);
    echo "Database created successfully";

    $pdo->close();

    $pdo = new PDO('mysql:host=$host;dbname=products', $user, $pass);
    $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

    // your create table code here
    . . .

如何使用PDO从mysql创建数据库和表？

2 个答案: