How to query if database exists in php

How to query whether the database exists in php: 1. Use PDO to determine whether the database exists; 2. Use SQL statements to determine whether the database exists.

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PHP determines whether the database exists

1. Two methods to determine whether the database exists:

1. Use PDO to determine whether the database exists

2. Use SQL statements to determine

2. Method 1 executes the code as follows:

//$config['dsn']的表示如下
$config["dsn"] => string(65) "mysql:host=127.0.0.1;port=3306;charset=utf8"
//$config['username']为数据库用户名， $config['password']：数据库密码

function isDBExist($config)
{
    $config['dsn'] = $this->parseDsn($config);//转换组为DSN字符串
 
    $conn = new PDO($config['dsn'], $config['username'], $config['password']);
    // 设置 PDO 错误模式为异常
    $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    $sql = "show databases;";
    // 使用 exec() ，因为没有结果返回
    $res = $conn->query($sql);
    $res = $res->fetchAll(PDO::FETCH_ASSOC);
    $database_list = [];
    foreach($res as $k => $v) {
        $database_list[] = $v['Database'];
    }
    if (in_array($config['database'],$database_list)) {
        return true; // 存在
    } else {
        return false;
    }
}
2. 方法二执行代码如下：
//$config['username']为数据库用户名

function isDBExist($config)
{
       try {
 
            $rs = Db::execute("use ".$db_config["database"]);
        }catch (Exception $e)
        {
            return false;//不存在
        }
        return true;
}

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