mysqli_fetch_query返回boolean [duplicate]

Question

This question already has an answer here:

• mysql_fetch_array()/mysql_fetch_assoc()/mysql_fetch_row()/mysql_num_rows etc… expects parameter 1 to be resource or result 32 answers

Good day, Im trying read all records from my table but I keep getting this error

message: 'Warning: mysql_fetch_array() expects parameter 1 to be mysqli_result, boolean given in

here is my code :

                 $conn =  mysqli_connect("localhost", "root", "") or die                (mysql_error()); //Connect to server

                 $username =    mysqli_real_escape_string($conn,$_POST['username']);

                $password = mysqli_real_escape_string($conn,$_POST['password']);

$bool = true;

             //mysql_connect("localhost", "root", "") or die(mysql_error());// connects to the server
            mysqli_select_db($conn,"first_db") or die("Cannot connect to the database");//connects to the db
            $query = ("select * from user");//
            $result = mysqli_query($conn,$query);//query the user table

            while($row = mysqli_fetch_array($result))//display all rows from the query
            {
            $table_users = $row['username'];//the first username row is passed on to $table_users,and so on until the query is finished
             if($username == $table_users)//checks if there are any  mixing fields
                {
                 $bool = false;//sets bool to false
                 Print '<script>alert("Username has been taken!")                                </script>';//prompts the user
                Print '<script>window.location.assign("register.php")</script>';//redirects user to register.php

                }

               }
                 if($bool)//sets bool to true
                   {
                    mysqli_query($conn,"INSERT INTO user (username,password) VALUES ('$username','$password')");//inserts the value to table users
                    Print '<script>alert("Successfully Registered!")    </script>';//prompts the user
                    Print '<script>window.location.assign("register.php")</script>';//redirects user to register.php
                   }

                    echo "Username entered is: ". $username. "<br/>";
                    echo "Password entered is: ". $password;
                   }
                  ?>

Answer 1

This is because you mixing mysql and mysqli.

This is problem with database connection

You have to write connection like this

$conn =  mysqli_connect("localhost", "root", "","first_db"); 

Instead of this:

$conn =  mysqli_connect("localhost", "root", ""); 
 mysqli_select_db($conn,"first_db") or die("Cannot connect to the database");