PHP中的$ _POST到CSV

I've a php file to export php data to csv.

But I've got the following error

Warning: mysql_num_fields() expects parameter 1 to be resource boolean given in C:\xampp\htdocs\exporttocsv3\export2csv.php on line 28

and

Warning: mysql_fetch_array() expects parameter 1 to be resource boolean given in C:\xampp\htdocs\exporttocsv3\export2csv.php on line 40

Form.php

<!DOCTYPE html>
<html>
<head>
    <title></title>
</head>
<body>

<form method="post" action="export2csv.php">
    <input type = "text" name ="wow" placeholder="Search by name">
<button  name="submit" type="submit">Wew</button>
</form>

</body>
</html>

export2csv.php

<?php

// Database Connection

$host="localhost";
$uname="root";
$pass="louchin";
$database = "phppot_examples";  

$connection=mysql_connect($host,$uname,$pass); 

echo mysql_error();

//or die("Database Connection Failed");
$selectdb=mysql_select_db($database) or die("Database could not be selected");  
$result=mysql_select_db($database)
or die("database cannot be selected <br>");



if (isset($_POST['submit'])) {

$name = $_POST['wow'];

$output = "";
$table = "toy"; 
$sql = mysql_query("SELECT id, name, code FROM $table WHERE (name LIKE '%$name%'");
$columns_total  = mysql_num_fields($sql);

// Get The Field Name

for ($i = 0; $i < $columns_total; $i++) {
    $heading    =   mysql_field_name($sql, $i);
    $output     .= '"'.$heading.'",';
}
$output .="
";

// Get Records from the table

while ($row = mysql_fetch_array($sql)) {
for ($i = 0; $i < $columns_total; $i++) {
$output .='"'.$row["$i"].'",';
}
$output .="
";
}

// Download the file

$filename =  "myFile.csv";
header('Content-type: application/csv');
header('Content-Disposition: attachment; filename='.$filename);

echo $output;
exit;
}   
?>

As you can see it's in mysql but I'll convert it later to mysqli query. Thank you for future answers

You've got lacking close parenthesis in your query. That's why it shows an error.

 $sql = mysql_query("SELECT id, name, code FROM $table WHERE (name LIKE '%$name%')")