if you end up after an csv import with anonymous field name set like COL1.. etc, and you need to rename and sanitize the field name based on the first record that contains the name, this is one (of many) posible solution.

renameField.php

<?php

function sanitize($str)
{
	$str = mb_strtolower($str, 'UTF-8');
	$search  = array(" - ", " ", "(", ")", "-", "/");
	$replace = array("_", '_', "", "", "", "_");
	$str = str_replace($search, $replace, $str);
	return $str;
}

// Preset
$db = "mydb";
$table = "my_table";

$mysqli = new mysqli("localhost", "user", "12345", $db);

if ($mysqli->connect_errno) {
    print_r($mysqli->connect_error);
    exit();
}

$query = "SELECT * FROM $table LIMIT 1";
$result = $mysqli->query($query);

while($row = $result->fetch_array(MYSQLI_NUM))
{
    $field['name'] = $row;
}

$result->free();

for ($i = 0; $i < count($field['name']); $i++)
{
	$fieldId = ($i+1);

	$sql = "SELECT character_maximum_length AS `maxLength` FROM information_schema.columns WHERE table_name = '$table' AND column_name = 'COL $fieldId'";
	$result = $mysqli->query($sql);
	$row = $result->fetch_assoc();

	$sqlAlter = "ALTER TABLE `$table` CHANGE `COL $fieldId` `" . sanitize($field['name'][$i]) . "` VARCHAR(". $row['maxLength'] .") NULL";
	$result->free();
	$mysqli->query($sqlAlter);

}

$mysqli->close();

echo "done!";