WHERE子句错误

我试图在HTML表的数据库中显示一个特定的值。声明如下：（这只是一个例子）

$sql = "SELECT * FROM tbl_trainings WHERE tbl_trainings.training='Meat Processing'";

我的问题是我有这样的声明（连接表）：

$sql="SELECT 
tbl_info.id, 
tbl_info.firstname, 
tbl_info.middlename, 
tbl_info.lastname, 
tbl_trainings.id,
tbl_trainings.training,
tbl_trainings.info_id
  FROM tbl_info, tbl_trainings
  WHERE tbl_info.id = info_id 
  ORDER BY tbl_info.id";

我试图在下面的语句中插入WHERE tbl_trainings.training='Meat Processing'：

$sql="SELECT 
tbl_info.id, 
tbl_info.firstname, 
tbl_info.middlename, 
tbl_info.lastname, 
tbl_trainings.id,
tbl_trainings.training,
tbl_trainings.info_id
  FROM tbl_info, tbl_trainings
  WHERE tbl_info.id = info_id, tbl_trainings.training='Meat Processing'
  ORDER BY tbl_info.id";

但我弄错了。错误为：

警告：mysql_fetch_array（）要求参数1为resource，布尔值在C:''wamp''www''CLphpTest''meatproc.php 中给定

有人能帮我纠正一下吗？（对不起，还是一个角落）

提前谢谢。