note 116243 added to mysqli.construct

mysqli can succeed in surprising ways, depending on the privileges granted to the user. For example, GRANT USAGE ON *.* TO 'myuser'@'localhost' IDENTIFIED BY PASSWORD 'mypassword'; GRANT ALL PRIVILEGES ON database_a.* TO 'myuser'@'localhost'; CREATE DATABASE database_b; <?php $db = new mysqli('localhost', 'myuser', 'mypassword', 'database_b'); if ($db->connect_error) { die('Connect Error (' . $db->connect_errno . ') ' . $mysqli->connect_error); } printf("SQLSTATE: %s\n", $this->db->sqlstate); printf("Warning Count: %s\n", $db->warning_count); $db->close(); ?> Will output: SQLSTATE: 00000 Warning Count: 0 So, life is good — you're connected to the database and executing mysqli methods. Except, life isn't good, because you aren't actually using database_b because myuser doesn't have any privileges on it. You won't catch this until you try to perform a later operation, when you'll get an error, "MYSQL Error: No database selected", and find yourself scratching your head and thinking "what do you mean, of course I have a database selected; I selected one when I called the constructor". As a result, you may want to perform an additional check after connecting to mysql, to confirm that you're actually connected not just to the mysql server, but to the actual database: <?php $db = new mysqli('localhost', 'myuser', 'mypassword', 'database_b'); if ($db->connect_error) { die('Connect Error (' . $db->connect_errno . ') ' . $mysqli->connect_error); } elseif ($result = $db->query("SELECT DATABASE()")) { $row = $result->fetch_row(); if ($row[0] != 'database_b') { //oops! We're connected to mysql, but not to database_b } } ?> ---- Server IP: 72.52.91.14 Probable Submitter: 2a00:1028:9195:ded2:3963:2813:5ab0:7b36 ---- Manual Page -- http://php.net/manual/en/mysqli.construct.php Edit -- https://master.php.net/note/edit/116243 Del: integrated -- https://master.php.net/note/delete/116243/integrated Del: useless -- https://master.php.net/note/delete/116243/useless Del: bad code -- https://master.php.net/note/delete/116243/bad+code Del: spam -- https://master.php.net/note/delete/116243/spam Del: non-english -- https://master.php.net/note/delete/116243/non-english Del: in docs -- https://master.php.net/note/delete/116243/in+docs Del: other reasons-- https://master.php.net/note/delete/116243 Reject -- https://master.php.net/note/reject/116243 Search -- https://master.php.net/manage/user-notes.php