PDO创建数据库和表 [英] PDO creating database and tables

问题描述

我目前正在努力工作。我将创建一个PHP脚本，将创建一个数据库和该数据库的所有表。我已经能够拼凑在一起的脚本创建数据库本身从这里读取和W3Schools，但是我很遗憾，如何使相同的脚本在新的数据库上创建表。这是我要创建一个新的数据库：

I'm currently struggling with an assignment. I am to create a PHP script that will create a database and all the tables for that database. I have been able to cobble together the script to create the database itself from reading here and W3Schools, however I am stumped as to how to have the same script create tables on that new database. Here's what I have to create a new database:

<?php
$servername = "localhost";
$username = "root";
$password = "mysql";

try {
$conn = new PDO("mysql:host=$servername", $username, $password);
$conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$sql = "CREATE DATABASE IF NOT EXISTS musicDB";
$conn->exec($sql);
echo "DB created successfully";
}
catch(PDOException $e)
{
echo $sql . "<br>" . $e->getMessage();
}

$conn = null;
?>

我试着跟着，然后用这个创建表：

I tried to follow on that to then create tables with this:

<?php
$servername = "localhost";
$username = "root";
$password = "mysql";

try {
$conn = new PDO("mysql:host=$servername", $username, $password);
$conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$sql = "CREATE DATABASE IF NOT EXISTS musicDB";
$sql = "use musicDB";
$sql = "CREATE TABLE IF NOT EXISTS ARTISTS (
ID int(11) AUTO_INCREMENT PRIMARY KEY,
artistname varchar(30) NOT NULL)";
$conn->exec($sql);
echo "DB created successfully";
}
catch(PDOException $e)
{
echo $sql . "<br>" . $e->getMessage();
}

$conn = null;
?>

但是这不工作，我得到以下错误：CREATE TABLE IF NOT EXISTS ARTISTS （11）AUTO_INCREMENT PRIMARY KEY，artistname varchar（30）NOT NULL）
SQLSTATE [3D000]：目录名称无效：1046未选择数据库

However that is not working and I get the following error: CREATE TABLE IF NOT EXISTS ARTISTS ( ID int(11) AUTO_INCREMENT PRIMARY KEY, artistname varchar(30) NOT NULL) SQLSTATE[3D000]: Invalid catalog name: 1046 No database selected

我告诉脚本使用新创建的表，然后为它创建表？而且我知道用户名和密码正在显示，但这是在我的笔记本电脑上运行，永远不会在任何地方，所以我不担心。

Basically, how do I tell the script to use the newly created table and then create tables for it? And I know the username and password are showing but this is running on my laptop and will never be anywhere so I'm not worried.

推荐答案

您只执行最后一条语句。您继续分配 $ sql ，但不执行这些语句。

You're only executing the last statement. You keep assigning to $sql, but not executing those statements.

try {
    $conn = new PDO("mysql:host=$servername", $username, $password);
    $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    $sql = "CREATE DATABASE IF NOT EXISTS musicDB";
    $conn->exec($sql);
    $sql = "use musicDB";
    $conn->exec($sql);
    $sql = "CREATE TABLE IF NOT EXISTS ARTISTS (
                ID int(11) AUTO_INCREMENT PRIMARY KEY,
                artistname varchar(30) NOT NULL)";
    $conn->exec($sql);
    echo "DB created successfully";
}
catch(PDOException $e)
{
    echo $sql . "<br>" . $e->getMessage();
}

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