php 的 mysqli_multi_query 不工作

Question

我一直在尝试执行多个查询，因此我寻找了一种更好的方法来执行此操作，并且我在 php 中阅读了mysqli_multi_query。

我自己尝试了一下看看结果，但它一直给我错误。代码如下:

$studid = $_GET['stud_id'];
$classcode = $_GET['class'];

$conn = new MySQLi($host, $username, $password, $dbname) or die('Can not connect to database');     

$sql = "SELECT * FROM tbl_students WHERE stud_id = '".$studid."'";
$sql.= "SELECT * FROM tbl_classes WHERE class_code = '".$classcode."'";

if (mysqli_multi_query($conn, $sql)) {
    do {
        /* store first result set */
        if ($result = mysqli_store_result($conn)) {
            while ($row = mysqli_fetch_row($result)) {
                $studname = $row[3].", ".$row[1];

            }
            mysqli_free_result($result);
        }
        /* print divider */
        if (mysqli_more_results($conn)) {
            printf("-----------------\n");
            $studname = $row['fname'];
        }
    } while (mysqli_more_results($conn));
}else{ echo "error";}

$conn->close();

使用上面的代码，它只会打印我设置的 else 语句中的错误。我还尝试将第二个查询更改为 $sql .= "SELECT * FROM tbl_classes WHERE class_code = '".$classcode."'"; 并尝试在第一个查询后面加上分号来告诉 SQL我已经完成了第一个查询，因为我将 2 个字符串放在一起，但仍然没有运气。

Answer 1

试试这个

$studid = $_GET['stud_id'];
$classcode = $_GET['class'];

$conn = new MySQLi($host, $username, $password, $dbname) or die('Can not connect to database');     

$sql = "SELECT * FROM tbl_students WHERE stud_id = '$studid';";
$sql.= "SELECT * FROM tbl_classes WHERE class_code = '$classcode'";

if ($conn->multi_query($sql)) {
    do {
        /* store first result set */
        if ($result = mysqli_store_result($conn)) {
            while ($row = mysqli_fetch_row($result)) {
                $studname = $row[3].", ".$row[1];

            }
            mysqli_free_result($result);
        }
        /* print divider */
        if (mysqli_more_results($conn)) {
            printf("-----------------\n");
            $studname = $row['fname'];
        }
    } while (mysqli_more_results($conn));
}else{ echo "error";}

$conn->close();