表中的列存在，但是SQL给出错误，提示“未知列”

Question

I have a table that has the column name Status, but when I run this code below it tells me:

Error: Unknown column 'help_box.status' in 'field list'

Code:

//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

What table is help_box.status in? You don't reference it in your FROM or your JOIN so it doesn't know where to look. It's trying to find a table named help_box and a column named status.