没有数据库名称的 Pdo 连接？

Question

I'm trying to create a CMS and I want to make my client life easier so I create the database by myself. I encountered a problem while trying to do this. The database isn't created so I can't connect with a PDO connection and mysql is deprecated so I can't use it. Do you have any advice for me on how I can create a PDO connection before the database is created? like a mysql_select_db() alternative?

Answer 1

You can start a PDO connection by this, correct me if I'm wrong:

$db = new PDO("mysql:host=localhost", 'user', 'pass');

The difference from this with a normal connection is the removed part dbname=[xx] , as you see.

Also a free tip when you want to use a UTF8 connection:

$db = new PDO("mysql:host=localhost;charset=UTF-8", 'user', 'pass');

In order to the comment of Yehonatan you can select a database by:

$db->exec('USE databaseName');

Answer 2

Simply drop the dbname= part:

try {
    $pdo = new PDO("mysql:host=localhost;", "user", "pass");
    $stmt = $pdo->query("SHOW DATABASES");
    var_dump($stmt->fetchAll(PDO::FETCH_ASSOC));
}
catch (PDOException $e) {
    echo $e->getMessage();
}

Gives me

array(11) {
  [0]=>
  array(1) {
    ["Database"]=>
    string(18) "information_schema"
  }
  [1]=>
  array(1) {
    ["Database"]=>
    string(5) "cdcol"
  }
  [2]=>
  array(1) {
    ["Database"]=>
    string(5) "chica"
  }
  [3]=>
  array(1) {
    ["Database"]=>
    string(9) "downloads"
  }
  [4]=>
  array(1) {
    ["Database"]=>
    string(5) "mysql"
  }
  [5]=>
  array(1) {
    ["Database"]=>
    string(18) "performance_schema"
  }
  [6]=>
  array(1) {
    ["Database"]=>
    string(10) "phpmyadmin"
  }
  [7]=>
  array(1) {
    ["Database"]=>
    string(8) "rishumon"
  }
  [8]=>
  array(1) {
    ["Database"]=>
    string(4) "test"
  }
  [9]=>
  array(1) {
    ["Database"]=>
    string(5) "users"
  }
  [10]=>
  array(1) {
    ["Database"]=>
    string(7) "webauth"
  }
}

as expected.

Answer 3

我发现唯一可行的方法是在运行任何查询之前使用$pdo->query('USE databasename')设置默认数据库。

Answer 4

Using an empty string also works, eg dbname=; no need to add more logic to get rid of all the dbname parts.

$db_name = '';

$pdo = new PDO(
    sprintf('mysql:host=%s;dbname=%s;charset=%s',
        $db_host, $db_name, $db_charset),
    $db_user,
    $db_pass
);