Question

以下mysqli查询无效。我需要将SET变量值分配给blink''space或null。但问题是在SET之后如果我使用任何变量然后它不工作。请告诉我，我对这个查询做了什么错误？

$q = mysqli_query($conn, "UPDATE photo_gallery 
                          SET $name_of_image_to_del=' ' 
                          WHERE id='$row_id'");

Answer 1

首先检查值是否存在，然后传入该查询： -

if (isset($name_of_image_to_del) && $name_of_image_to_del != '') {
    $q = mysqli_query($conn, "UPDATE photo_gallery SET $name_of_image_to_del=' ' WHERE id='$row_id'");
}

Answer 2

我认为您想要更新columnName的值，即Dynamic，

请查找以下代码：

<?php
    $conn = mysqli_connect("localhost","root","password","db");
    $columnName = 'columnName';
    $valueToCheck = 'makeMeBlank';
    $sql = "UPDATE tableName SET $columnName=' ' WHERE id='$valueToCheck'";
    $q = mysqli_query($conn, $sql);
?>

无法动态生成MYSQL查询

2 个答案: