“没有选择数据库”

Question

So I am having trouble inserting data into my database. The current error I have is a "No database selected" error but I can't see where the issue is. My code is:

<?php

$con=mysqli_connect("localhost","root","","db_test");

// Check connection

if (mysqli_connect_errno())
  {
  echo "Failed to connect to MySQL: " . mysqli_connect_error();
  }

$firstname=$_POST['firstnameReg']; 
$surname=$_POST['surnameReg'];
$mypassword=$_POST['passwordReg']; 
$email=$_POST['emailReg'];


$result= mysql_query("INSERT INTO tbl_customers (firstname, lastname, email, password) VALUES ('$firstname', '$surname', '$email', '$mypassword'");

echo "$firstname", "$surname", "$mypassword", "$email";

if($result)
{
    echo "Success!";
}
else
{
    die(mysql_error());
}

mysqli_close($con);
?>

Can you see any errors? I know it's not protected against SQL injection, it's just a test project. Thank you.

Answer 1

Instead of mysql_query which is from the wrong library, you should use mysqli_query

$result= mysql_query("INSERT INTO tbl_customers (firstname, lastname, email, password) VALUES ('$firstname', '$surname', '$email', '$mypassword'");

So in your case, you're also missing the closing parenthesis from the VALUES:

$result = mysqli_query($con, "INSERT INTO tbl_customers (firstname, lastname, email, password) VALUES ('$firstname', '$surname', '$email', '$mypassword')");

Taking the opportunity you should also implement prepared statement to avoid SQL injection:

$sql = "INSERT INTO tbl_customers (firstname, lastname, email, password) VALUES (?, ?, ?, ?)";
if (!$insert = $con->prepare($sql))
    die('Query failed: (' . $con->errno . ') ' . $con->error);

if (!$insert->bind_param('ssss', $firstname, $surname, $email, $mypassword))
    die('Binding parameters failed: (' . $insert->errno . ') ' . $insert->error);

if (!$insert->execute())
    die('Execute failed: (' . $insert->errno . ') ' . $insert->error);
else
    echo "Success!";

mysqli_close($con);