php7.4对低版本的mysql内置函数的兼容支持

对一些低版本运行的php程序改造或许会有些用哦

//--高版本的mysql支持
$dbhost = DB_HOST;
$dbport = 3306;
$dbuser = DB_USER;
$dbpass = DB_PASSWD;
$dbname = DB_NAME;
if(!function_exists('mysql_connect')){
    function mysql_connect($dbhost, $dbuser, $dbpass){
        global $dbport;
        global $dbname;
        global $mysqli;
        $mysqli = mysqli_connect("$dbhost:$dbport", $dbuser, $dbpass, $dbname);
        return $mysqli;
    }
    function mysql_select_db($dbname){
        global $mysqli;
        return mysqli_select_db($mysqli,$dbname);
    }
    function mysql_fetch_array($result){
        return mysqli_fetch_array($result);
    }
    function mysql_fetch_assoc($result){
        return mysqli_fetch_assoc($result);
    }
    function mysql_fetch_row($result){
        return mysqli_fetch_row($result);
    }
    function mysql_query($query){
        global $mysqli;
        return mysqli_query($mysqli,$query);
    }
    function mysql_escape_string($data){
        global $mysqli;
        return mysqli_real_escape_string($mysqli, $data);
    }
    function mysql_real_escape_string($data){
        return mysql_real_escape_string($data);
    }
    function mysql_close(){
        global $mysqli;
        return mysqli_close($mysqli);
    }
    function mysql_num_rows($result){
        return mysqli_num_rows($result);
    }
    function mysql_num_fields($result){
        return mysqli_num_fields($result);
    }
    function mysql_insert_id(){
        global $mysqli;
        return $mysqli->insert_id;
    }
    function mysql_error(){
        global $mysqli;
        return mysqli_error($mysqli);
    }
    function mysql_errno(){
        global $mysqli;
        return mysqli_errno($mysqli);
    }
    function mysql_affected_rows(){
        global $mysqli;
        return mysqli_affected_rows($mysqli);
    }
    function mysql_get_server_info(){
        global $mysqli;
        return mysqli_get_server_info($mysqli);
    }
    define('MYSQL_ASSOC',0);
}