检查数据库凭证是否有效？

Question

I'm building a small self-hosted app which requires database usage. I'd like to validate that the user inputted database credentials are valid, before they're actually saved. What could I do to check whether or not a connection is valid, would it be as simple as?

$conn = mysql_connect($db_name, $db_user, $db_pass); mysql_select_db($db_name);

if($conn) {
    mysql_close($conn);
    // Do stuff if connection is valid
} else {
    mysql_close($conn);
    // Do stuff if connection is invalid
    }

Would I even need to close the connection if it's invalid? (Within the else{} statement. I took a look at mysql_ping() but it doesn't really seem to be what I need.

Answer 1

如果凭据无效，则无需关闭连接，因为它不会首先打开。

Answer 2

also frequently used is 'die' which allows you to print a message before stopping execution of the script:

$conn = mysql_connect($db_name, $db_user, $db_pass) or die('the error message');

or for debugging purposes the following is frequently used:

$conn = mysql_connect($db_name, $db_user, $db_pass) or die(mysql_error());

which will print the mysql error such as a warning about wrong credentials