语法错误：意想不到的字符串！！

php代码：$sql="insert into message ('id','user','title','comment','lastdate') value ('.$di','.$user','.$title','.$comment','.$lastdate');
mysql_query($sql,$connec);
echo ("<script type='text/javascript'> alert ('添加成功'); location.href='index.php'</script>");
?>

语法错误：意想不到的字符串！！echo ()里面错误。是不是要用转义字符？？

Parse error: syntax error, unexpected T_STRING in

$sql="insert into message ('id','user','title','comment','lastdate') value ('{$di}','{$user}','{$title}','{$comment}','{$lastdate}');";