mysql_select_db（）期望参数2是资源，字符串在

Question

我遇到了新的错误

mysql_select_db（）期望参数2是资源，第12行的C：\ Apache24 \ htdocs \ login \ check_login.php中给出的字符串 数据库名称不可用！

mysql_select_db（＆＃39; localhost＆＃39;，＆＃39; test＆＃39;）或死亡（＆＃34;数据库名称不可用！＆＃34;）;

Answer 1

<?php
$con=mysqli_connect("localhost","my_user","my_password");
// Check connection
if (mysqli_connect_errno()) {
  echo "Failed to connect to MySQL: " . mysqli_connect_error();
}
// Change database to "test"
mysqli_select_db($con,"test");
mysqli_close($con);
?>