查询正确排序，但没有正确显示所有结果

Question

下面的查询有效，但我似乎有一个奇怪的错误。 users表中的第一个用户可以看到所有其他用户与其关联的所有帮助问题。但数据库中的第二个用户只能通过他们在表中的第一个人获得帮助问题，并且该查询会忽略该表中其他人对第二个人的结果。

我猜它与括号有关吗？

代码：

//Unseen 
$variis = "Need Help"; 
$myid = "This is the user's id;" 

$sql = "select car_help.car_id, agent_names.agent_name, help_box.status, 
car_help.why_car, car_help.date_time_added, car_help.just_date, 
car_help.type, agent_names.agent_id 
from car_help LEFT JOIN agent_names on car_help.agent_whois = agent_names.agent_id 
where agent_names.system_id = '$myid' and car_help.system_id='$myid' 
and added_by <> '$myid' and help_box.status = '$variis' 
UNION 
select magazine_help.note_id, agent_names.agent_name, help_box.status, 
magazine_help.note_name, magazine_help.date_time_added, 
magazine_help.just_date, magazine_help.type, agent_names.agent_id 
from magazine_help LEFT JOIN agent_names on 
magazine_help.agent_id = agent_names.agent_id 
where agent_names.system_id='$myid' and 
magazine_help.system_id = '$myid' and added_by <> '$myid' 
and help_box.status = '$variis' 
UNION 
select motorcycle_help.rand_id, agent_names.agent_name, 
help_box.status, motorcycle_help.rand_name, motorcycle_help.date_time_added,  
motorcycle_help.just_date, motorcycle_help.type, agent_names.agent_id 
from motorcycle_help LEFT JOIN agent_names ON 
motorcycle_help.by_who = agent_names.agent_id 
where agent_names.system_id = '$myid' and 
motorcycle_help.system_id='$myid' and added_by <> '$myid' 
and help_box.status = '$variis' 
UNION 
select mobile_questions.bal_test_id, agent_names.agent_name, 
help_box.status, mobile_questions.bal_why, mobile_questions.date_time_added, 
mobile_questions.just_date, mobile_questions.type, agent_names.agent_id 
from mobile_questions LEFT JOIN agent_names ON 
mobile_questions.agent_who_ordered = agent_names.agent_id 
where agent_names.system_id = '$myid' and 
mobile_questions.system_id='$myid' and added_by <> '$myid' 
and help_box.status = '$variis' 
ORDER BY date_time_added DESC LIMIT $startrow, 20"; 

$result = mysql_query($sql); 

$query = mysql_query($sql) or die ("Error: ".mysql_error()); 


if ($result == "") 
{ 
echo ""; 
} 
echo ""; 


$rows = mysql_num_rows($result); 

if($rows == 0) 
{ 
print(""); 

} 
elseif($rows > 0) 
{ 
while($row = mysql_fetch_array($query)) 
{ 

$row1 = $row['row_name']; 


print("$row1"); 
} 

} 

Answer 1

where agent_names.system_id = '$myid' and 
motorcycle_help.system_id='$myid' and added_by <> '$myid' 
and help_box.status = '$variis' 

只返回数据，如果所有的true。如果第二个人在所有三个字段中没有匹配的ID，它将不会返回您的期望。如果$variis为空，则创建一个应该替换调用变量的默认ID。可能需要一个或一个声明。如果你打算使用回声棒，print可以做同样的事情。