我正在应用这个sql compersion查询，但收到语法错误 - i am applying this sql compersion query but receiving syntax error

这是我在插入时的代码，它可以工作，但在比较时显示解析语法错误

// attempt insert query execution
$sql = "INSERT INTO availer (source_name, dstntn_name, sou_date, flight_no, sou_weight, contact_name, contact_no) VALUES ('$source_name', '$dstntn_name', '$sou_date', '$flight_no', '$sou_weight', '$contact_name', '$contact_no')";
if(mysqli_query($link, $sql)){
    $sql ="SELECT availer.id, availer.source_name,availer.dstntnn_name,availer.sou_date,availer.sou_weight FROM availer availer
    WHERE EXISTS (SELECT * FROM provider provider
    WHERE provider.source_name = availer.source_name AND provider.dstntn_name = availer.dstntn_name AND provider.sou_date = availer.sou_date AND provider.flight_no = availer.flight_no");
    print $query;
} else{
    echo "ERROR: Could not able to execute $sql. " . mysqli_error($link);
}

您错误放置了"标记。您的代码应该是这样的。

 $sql = "INSERT INTO availer (source_name, dstntn_name, sou_date, flight_no, sou_weight, contact_name, contact_no) VALUES ('$source_name', '$dstntn_name', '$sou_date', '$flight_no', '$sou_weight', '$contact_name', '$contact_no')";
        if(mysqli_query($link, $sql)){
            $sql ="SELECT availer.id, availer.source_name,availer.dstntnn_name,availer.sou_date,availer.sou_weight FROM availer availer
            WHERE EXISTS (SELECT * FROM provider provider
            WHERE provider.source_name = availer.source_name AND provider.dstntn_name = availer.dstntn_name AND provider.sou_date = availer.sou_date AND provider.flight_no = availer.flight_no)";
            print $query;
        } else{
            echo "ERROR: Could not able to execute $sql. " . mysqli_error($link);
        }

<?php
/* Attempt MySQL server connection. Assuming you are running MySQL
server with default setting (user 'root' with no password) */
$link = mysqli_connect("localhost", "root", "", "prog_db");
// Check connection
if($link === false){
    die("ERROR: Could not connect. " . mysqli_connect_error());
}
 // Escape user inputs for security
$source_name = mysqli_real_escape_string($link, (isset($_POST['source'])));
$dstntn_name = mysqli_real_escape_string($link,(isset($_POST['dstntn'])));
$sou_date = mysqli_real_escape_string($link,(isset($_POST['date'])));
$flight_no = mysqli_real_escape_string($link,(isset($_POST['flightno'])));
$sou_weight = mysqli_real_escape_string($link,(isset($_POST['weight'])));
$contact_name = mysqli_real_escape_string($link,(isset($_POST['name'])));
$contact_no = mysqli_real_escape_string($link,(isset($_POST['contact'])));

// attempt insert query execution
$sql = "INSERT INTO availer (source_name, dstntn_name, sou_date, flight_no, sou_weight, contact_name, contact_no) VALUES ('$source_name', '$dstntn_name', '$sou_date', '$flight_no', '$sou_weight', '$contact_name', '$contact_no')";
if(mysqli_query($link, $sql)){ $sql ="SELECT availer.id, availer.source_name,availer.dstntnn_name,availer.sou_date,availer.sou_weight FROM availer availer
            WHERE EXISTS (SELECT * FROM provider provider
            WHERE provider.source_name = availer.source_name AND provider.dstntn_name = availer.dstntn_name AND provider.sou_date = availer.sou_date AND provider.flight_no = availer.flight_no)";
            $result = mysql_query($sql,$link);
while($row = mysql_fetch_array($result)) {
echo $row['SOURCE_name'];
}
   } 
else{
    echo "ERROR: Could not able to execute $sql. " . mysqli_error($link);
}
// close connection
mysqli_close($link);
but i am not able to fatch the result on the webpage .

您应该编写

        // Check connection
        if($link === false){
            die("ERROR: Could not connect. " . mysqli_connect_error());
        }
    if (isset ($_POST['source'], $_POST['dstntn'], $_POST['date'], $_POST['flightno'],$_POST['weight'],$_POST['name'], $_POST['contact'])){
     $source_name = mysqli_real_escape_string($link,$_POST['source']);
        $dstntn_name = mysqli_real_escape_string($link,$_POST['dstntn']);
        $sou_date = mysqli_real_escape_string($link,$_POST['date']);
        $flight_no = mysqli_real_escape_string($link,$_POST['flightno']);
        $sou_weight = mysqli_real_escape_string($link,$_POST['weight']);
        $contact_name = mysqli_real_escape_string($link,$_POST['name']);
        $contact_no = mysqli_real_escape_string($link,$_POST['contact']);

        // attempt insert query execution
        $sql = "INSERT INTO availer (source_name, dstntn_name, sou_date, flight_no, sou_weight, contact_name, contact_no) VALUES ('$source_name', '$dstntn_name', '$sou_date', '$flight_no', '$sou_weight', '$contact_name', '$contact_no')";
        if(mysqli_query($link, $sql)){ $sql ="SELECT availer.id, availer.source_name,availer.dstntnn_name,availer.sou_date,availer.sou_weight FROM availer availer
                    WHERE EXISTS (SELECT * FROM provider provider
                    WHERE provider.source_name = availer.source_name AND provider.dstntn_name = availer.dstntn_name AND provider.sou_date = availer.sou_date AND provider.flight_no = availer.flight_no)";
                    $result = mysql_query($sql,$link);
        while($row = mysql_fetch_array($result)) {
        echo $row['SOURCE_name'];
        }
           } 
        else{
            echo "ERROR: Could not able to execute $sql. " . mysqli_error($link);
        }
    }
        // close connection
        mysqli_close($link);