php 警告：mysql_fetch_assoc() 期望参数 1 是资源，布尔值给定
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Warning: mysql_fetch_assoc() expects parameter 1 to be resource, boolean given
提问by scarhand
i am getting this error when trying to perform the following query:
尝试执行以下查询时出现此错误：
$sql = mysql_query("select c.id as id_car, c.year, c.make, c.model, c.type, c.colour,
(select count(*) from `parts` where `id_car`=c.id and `is_packaged`='yes') as partcount
from `cars` as c
where partcount > 0
group by c.id
order by `id` desc");
the problem seems to be the where partcount > 0. it seems to be seeing the 0 as a boolean when trying to make the comparison?
问题似乎是where partcount > 0. 尝试进行比较时似乎将 0 视为布尔值？
回答by GordonM
The value of $sql is probably false. This happens if the query you tried to execute failed to execute, usually due to a syntax error in the SQL.
$sql 的值可能是假的。如果您尝试执行的查询未能执行，通常是由于 SQL 中的语法错误，则会发生这种情况。
Generally, you want your query code to look like this:
通常，您希望查询代码如下所示：
if ($result = mysql_query ('SELECT * FROM foo WHERE bar = \'baz\''))
{
// resultset processing goes here
while ($row = mysql_fetch_assoc ($result))
{
}
}
else
{
echo (mysql_error ());
}
