Question

我的代码中有一部分带有一些似乎没有正常工作的elseif条件。我已经建立了一个条件下拉表格，到目前为止大部分都在工作，除非它到达其他几个地方。

我正在使用JS通过GET将下拉选项名称发送到我的PHP脚本，这似乎很奇怪。对于大多数表单，它从MySQL查询中提取下一个下拉列表的选项，但是对于第一个drop，我刚刚使用了一些elseifs来使它不那么复杂。您可以查看实时剧本 here. 以下是给我带来麻烦的部分（这是最后两个）：

if (isset($_GET['setpoint'])) {
    while ($row = mysql_fetch_array($result)) {
        echo "<option value='" . $row{'stp'} . "'>" . $row{'stp'} . "</option>";
    }
} elseif (isset($_GET['power'])) {
    echo "<option>Please Choose Setpoint Options</option>";
    while ($row = mysql_fetch_array($result)) {
        $row{'stp'} = ucfirst($row{'stp'}); //capitalizes the first letter; necessary?
        echo "<option value='" . $row{'stp'} . "'>" . $row{'stp'} . "</option>";
    }
} elseif (isset($_GET['source'])) {
    echo "<option>Please Choose Input Range</option>";
    while ($row = mysql_fetch_array($result)) {
        echo "<option value='" . $row{'sir'} . "'>" . $row{'sir'} . "</option>";
    }
} elseif (isset($_GET['type']) && $_GET['type'] = "Digital") {
    echo "<option>Please Choose Input Source</option>";
    echo "<option value='RS232C'>RS232C</option><option value='RS422'>RS422</option><option value='RS485'>RS485</option><option value='current loop'>current loop</option>";
} elseif (isset($_GET['type']) && $_GET['type'] = "Analog") {
    echo "<option>Please Choose Input Source</option>";
    echo "<option value='DC current'>DC Current</option><option value='DC voltage'>DC Voltage</option><option value='AC current'>AC Current</option><option value='AC voltage'>AC Voltage</option><option value='process'>Process</option><option value='thermocouple'>Thermocouple</option><option value='RDT'>rdt</option>";
}

第一个下拉列表会将$_GET['type']设置为'模拟'或'数字'，但无论选择哪个选项$_GET['type']，都会运行第一个检查$_GET['type']的elseif已设定。如果$_GET['type'] = 'Analog'那么它应该返回最后一个elseif而不是倒数第二个。

这是大多数参考脚本：

//prevents injections
//any order
isset($_GET['type'])?$type = urldecode($_GET['type']):"";
//$type = mysql_real_escape_string(urldecode($_GET['type']));
isset($_GET['source'])?$source = mysql_real_escape_string(urldecode($_GET['source'])):"";
isset($_GET['range'])?$power = mysql_real_escape_string(urldecode($_GET['range'])):"";
isset($_GET['setpoint'])?$setpoint = mysql_real_escape_string(urldecode($_GET['setpoint'])):"";

//forms the query depending on what data is recieved through GET
//first option on the bottom; last option on the top to avoid conflicts 
if (isset($_GET['setpoint'])) {
    $query = "SELECT DISTINCT stp FROM meters WHERE sio='$range' AND pso='$power' AND stp='$setpoint' ORDER BY model";
} elseif (isset($_GET['power'])) {
    $query = "SELECT DISTINCT stp FROM meters WHERE sio='$range' AND pso='$power' ORDER BY model";
} elseif (isset($_GET['range'])) {
    $query = "SELECT DISTINCT pso FROM meters WHERE sio='$range' ORDER BY model";
} elseif (isset($_GET['source'])) {
    $query = "SELECT DISTINCT sir FROM meters WHERE sio LIKE '%$source%' ORDER BY sir";
}

//creates a result array from query results
isset($query)?$result = mysql_query($query):"";

//outputs dropdown options dependent on what GET variables are set
//first option on the bottom; last option on the top to avoid conflicts
if (isset($_GET['setpoint'])) {
    while ($row = mysql_fetch_array($result)) {
        echo "<option value='" . $row{'stp'} . "'>" . $row{'stp'} . "</option>";
    }
} elseif (isset($_GET['power'])) {
    echo "<option>Please Choose Setpoint Options</option>";
    while ($row = mysql_fetch_array($result)) {
        $row{'stp'} = ucfirst($row{'stp'}); //capitalizes the first letter; necessary?
        echo "<option value='" . $row{'stp'} . "'>" . $row{'stp'} . "</option>";
    }
} elseif (isset($_GET['source'])) {
    echo "<option>Please Choose Input Range</option>";
    while ($row = mysql_fetch_array($result)) {
        echo "<option value='" . $row{'sir'} . "'>" . $row{'sir'} . "</option>";
    }
} elseif (isset($_GET['type']) && $_GET['type'] = "Digital") {
    echo "<option>Please Choose Input Source</option>";
    echo "<option value='RS232C'>RS232C</option><option value='RS422'>RS422</option><option value='RS485'>RS485</option><option value='current loop'>current loop</option>";
} elseif (isset($_GET['type']) && $_GET['type'] = "Analog") {
    echo "<option>Please Choose Input Source</option>";
    echo "<option value='DC current'>DC Current</option><option value='DC voltage'>DC Voltage</option><option value='AC current'>AC Current</option><option value='AC voltage'>AC Voltage</option><option value='process'>Process</option><option value='thermocouple'>Thermocouple</option><option value='RDT'>rdt</option>";

同样，您可以查看实时脚本here.

Answer 1

$_GET['type'] = "Digital"是作业，而不是支票。

您需要的是

$_GET['type'] == "Digital"

与$_GET['type'] = "Analog"

相同

应该是

$_GET['type'] == "Analog"

此外，与Darkbee一样，请使用PDO或MySQLi

Answer 2

当我想要比较运算符equals时，你正在分配$ _GET ['type']：

$_GET['type'] = "Digital"

变为

$_GET['type'] == "Digital"

Answer 3

尝试

elseif (isset($_GET['type']) && $_GET['type'] == "Digital")

和

elseif (isset($_GET['type']) && $_GET['type'] == "Analog")

两个等号是一个等号是一个赋值（总是会返回真值）

elseif条件的问题

3 个答案: