Php 当查询返回零行时，查询和while循环无法正常工作

当行数>0时，解析行的我的查询和while循环可以正常工作，但当=0时则不能正常工作

当返回的行数为0时，似乎跳过了整个while循环。请参阅注释，其中$activeCount被强制设置为=0，并且不会执行并显示以下错误消息

在下面的代码之前，在数组$errorMessages[]中设置了一条默认错误消息，并在触发器发生时更新和添加该消息。当查询中返回0行时，$error\u NoActives的更新不会发生

这是相关代码

//fetch the user's active posts and their count
$fetch = mysql_query("SELECT SQL_CALC_FOUND_ROWS * FROM (
    SELECT propertyID, streetAddress, city3, city2 FROM residence.property
    INNER JOIN contact ON residence.contact.ContactID = residence.property.ContactID
    WHERE residence.contact.contactEmailAddress1 ='$contactEmailAddress1' AND activePosting = '1') props,
    (SELECT FOUND_ROWS() AS 'activeCount') actives;")
    or die('<li class=error>Ooops</li>'. mysql_error());

//create HTML li items to show each posting and create jQuery to insert to a div
$rowCount = 0;
while ($row = mysql_fetch_array($fetch)) {
    $activeCount = $row["activeCount"];
    //$activeCount = 0; //test - get default error message, seems next 3+ lines are not executing when query has 0 rows
    if( $activeCount == 0 ) {
    $error_NoActives = "<li>You have $activeCount active postings.</li>";
    //don't get this message with 0 active posts, get default error
    $errorMessages[0] = $error_NoActives;
    } else {
        //$activeCount displays correctly if non-zero
        $error_NumberOfActives = "<ul>Welcome back. You have $activeCount active postings.
        //do stuff using $rowCount. Construct li items.
        $rowCount++;
        }
    }
}

我怀疑我不了解while循环，或者MySQL的find_行和SQL_CALC_find_行

---

无论如何，当查询返回0行时，$error\u NoActives语句没有执行。

while循环没有运行，因为您有0行，所以没有任何东西可以循环。如果行数超过0，则在WHILE周围设置if语句；如果行数为0，则在else中可以使用代码。还修复了欢迎消息中的语法错误

//fetch the user's active posts and their count
$fetch = mysql_query("SELECT SQL_CALC_FOUND_ROWS * FROM (
    SELECT propertyID, streetAddress, city3, city2 FROM residence.property
    INNER JOIN contact ON residence.contact.ContactID = residence.property.ContactID
    WHERE residence.contact.contactEmailAddress1 ='$contactEmailAddress1' AND activePosting = '1') props,
    (SELECT FOUND_ROWS() AS 'activeCount') actives;")
    or die('<li class=error>Ooops</li>'. mysql_error());
//create HTML li items to show each posting and create jQuery to insert to a div
$rowCount = 0;
if( mysql_num_rows($fetch) > 0 )
{
    while ($row = mysql_fetch_array($fetch)) {
        $activeCount = $row["activeCount"];
        //$activeCount = 0; //test - get default error message, seems next 3+ lines are not executing when query has 0 rows

            //$activeCount displays correctly if non-zero
            $error_NumberOfActives = "<ul>Welcome back. You have $activeCount active postings.";
            //do stuff using $rowCount. Construct li items.
            $rowCount++;
            }
    }
}
else {
    $error_NoActives = "<li>You have $activeCount active postings.</li>";
    //don't get this message with 0 active posts, get default error
    $errorMessages[0] = $error_NoActives;
}

---

while循环仅在有结果时运行。这是正常的，因为如果它试图在没有结果的情况下运行，$row中的所有值都将为null

正确的方法是使用mysql\u num\u行：

if(mysql_num_rows($fetch)) {
    while($row = mysql_fetch_assoc($fetch)) {
        $error_NumberOfActives = "<ul>Welcome back. You have $activeCount active postings.
        //Do stuff with $row.
    }
} else {
    $error_NoActives = "<li>You have $activeCount active postings.</li>";
}

---

就是说，您可以更好地处理错误。

您的代码末尾缺少一个双引号……值得指出的是，PHP中的mysql\u xxx已被弃用，不推荐使用。如果可能的话，您应该将代码切换为使用PDO库。Styphon，它可以正常工作。我还学到了一些书中没有的while循环。我很感谢你关于另外两点的建议。非常感谢，尼尔斯，谢谢。你的代码也可以用，但是Styphon先发布了。请查看发布的时间，但不要担心=对不起，是我的错。也许它们是按相反的顺序显示的。

$query = "mysqlquery";
if(mysql_query($query)) {
} else {
    //some error code
}