I keep getting this error i don't understand what's going on mysqli_select

I'm trying to get all the posts on the database to be listed in the home page

Fatal error: Uncaught TypeError: mysqli_select_db(): Argument #1 ($mysql) must be of type mysqli, string given in C:\xampp\htdocs\myblog\user_homepage.php:139 Stack trace: #0 C:\xampp\htdocs\myblog\user_homepage.php(139): mysqli_select_db('myblog', Object(mysqli)) #1 {main} thrown in C:\xampp\htdocs\myblog\user_homepage.php on line 139

<?php
include 'auth.guard.php';
include 'db_connection.php'

?>

<!DOCTYPE html>
<html lang="en">
<head>
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>regestration</title>
<style>
    /* padding on document's body to prevent the content
    to go underneath the header and footer */
    body{        
        padding-top: 60px;
        padding-bottom: 40px;
        box-sizing: border-box
    }
    /* Full-width input fields */
input[type=text], input[type=password] {
  width: 100%;
  padding: 15px;
  margin: 5px 0 22px 0;
  display: inline-block;
  border: none;
  background: #f1f1f1;
}

input[type=text]:focus, input[type=password]:focus {
  background-color: #ddd;
  outline: none;
}

hr {
  border: 1px solid #f1f1f1;
  margin-bottom: 25px;
}

/* Set a style for all buttons */
button {
  background-color: #04AA6D;
  color: white;
  padding: 14px 20px;
  margin: 8px 0;
  border: none;
  cursor: pointer;
  width: 100%;
  opacity: 0.9;
}

button:hover {
  opacity:1;
}

/* Extra styles for the cancel button */
.cancelbtn {
  padding: 14px 20px;
  background-color: #f44336;
}

/* Float signup buttons and add an equal width */
.cancelbtn, .signupbtn {
  float: left;
  width: 50%;
}

    .fixed-header, .fixed-footer{
        width: 100%;
        position: fixed;        
        background: #333;
        padding: 10px 0;
        color: #fff;
    }
    .fixed-header{
        top: 0;
    }
    .fixed-footer{
        bottom: 0;
    }
    .container{
        width: 80%;
        margin: 0 auto; /* Center the DIV horizontally */
        padding: 16px;
    }
    nav a{
        color: #fff;
        text-decoration: none;
        padding: 7px 25px;
        display: inline-block;
    }

table {
  border-collapse: collapse;
  width: 100%;
}

th, td {
  text-align: left;
  padding: 8px;
  border: 2px solid #f2f2f2;
}

tr:nth-child(even){background-color: #f2f2f2}

th {
  background-color: #04AA6D;
  color: white;
}
/* Clear floats */
.clearfix::after {
  content: "";
  clear: both;
  display: table;
}

/* styles for cancel button and signup button on extra small screens */
@media screen and (max-width: 300px) {
  .cancelbtn, .signupbtn {
     width: 100%;
  }
}
</style>
</head>
<body>
    <div >
        <div >
            <nav>
                <a href="user_homepage.php">Home</a>
                <a href="update_user_details_functionality.php">user profile</a>
                <a href= "logout.php">log out</a>
                
            </nav>
        </div>
    </div>
    
    <?php

$db = mysqli_select_db("myblog", $conn);

//finds the data stored in the database
$db = mysqli_select_db("myblog", $conn);
$query = mysqli_query("select * from posts", $conn);
$result = $conn->query($sql);
//making a table for the output
echo "<table border='1' <tr><th>ID</th> <th>post_date</th> <th>Price</th></tr>";
if ($result->posts> 0) {
    // output data of each row using a loop
    while($row = $result->fetch_assoc()) {
        echo "<tr><td>" . $row["post_id"]. "</td>" . "<td>" .$row["post_text"]. "</td>" . "<td>" . $row["post_date"] . "</td>" .  "<td>" . $row["category"] . "</td>" . "<td>" .  $row["price"] . "</td>" . "<td><img src='assets/" .   $row["post_id"]  . ".jpg' width='75'></td>";
        
echo "<input type='text' name='pcode' value='"  . $row["post_id"]. "'>";
echo "<input type='text' name='pname' value='"  . $row["post_text"]. "'>";
        
;
        
        for ($optionIndex=1; $optionIndex <= 15; $optionIndex  ){
            echo '<option>' . $optionIndex . '</option>';
        }

    }
echo "</table>";
} else {
    echo "0 results";
}
$conn->close();
?>

</div>


    <div >
        <div >Copyright &copy; 2021 Your Company</div>        
    </div>
</body>
</html>

CodePudding user response：

You have the arguments to mysqli_select_db flipped around (in both cases).

mysqli_select_db("myblog", $conn);

should be

mysqli_select_db($conn, "myblog");