How to delete part of the array data in php and synchronize it to the database

When developing, we often need to use arrays to store and operate data. However, as the development process proceeds, the data in the array will continue to be added or modified, and at this time we will inevitably need to delete some elements in the array. In PHP, deleting elements in an array can be achieved in various ways, such as using the unset() function or array_splice() function. But what if you need to synchronize the deleted array data to the database? This article will give you a detailed understanding of how PHP deletes partial data from an array and synchronizes it to the database.

1. Use the unset() function to delete array elements

The unset() function is used to delete an element in a variable or array. The specific steps to use this function to delete array elements are as follows:

1. First define an array variable and set the index value of the element to be deleted.
2. Then use the unset() function to delete the element at the specified index.
3. Finally, store the deleted array in the database.

The sample code is as follows:

<?php
// 定义数组变量
$arr=array("a"=>"Volvo","b"=>"BMW","c"=>"Toyota","d"=>"Honda");

// 删除指定索引处的元素
unset($arr["b"]);

// 将删除后的数组存入数据库中
// ......
?>

2. Use the array_splice() function to delete array elements

array_splice() function is used to delete elements in the array, and can delete elements after Then fill the empty space after deletion with other elements of the array. The specific steps to use this function to delete array elements are as follows:

1. First define an array variable and set the index value of the element to be deleted and the number of elements to be deleted.
2. Then use the array_splice() function to delete the specified number of elements at the specified index and rearrange the array.
3. Finally, store the deleted array in the database.

The sample code is as follows:

<?php
// 定义数组变量
$arr=array("Volvo","BMW","Toyota","Honda");

// 删除指定索引处指定数量的元素
array_splice($arr,1,2);

// 将删除后的数组存入数据库中
// ......
?>

3. Synchronize the deleted array to the database

In actual development, delete the elements in the array and store the deleted array The steps for synchronizing to the database are generally as follows:

1. Connect to the database.
2. Query the data of the array elements to be deleted.
3. Delete the array (you can use the unset() function or array_splice() function).
4. Update data in the database (you can use INSERT, UPDATE or DELETE statements).

The specific code implementation is as follows:

<?php
// 连接数据库
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDB";

$conn = mysqli_connect($servername, $username, $password, $dbname);
if (!$conn) {
    die("连接失败: " . mysqli_connect_error());
}

// 查询要被删除的数组元素的数据
$sql = "SELECT id FROM MyGuests WHERE lastname=&#39;Doe&#39;";
$result = mysqli_query($conn, $sql);

// 定义数组变量
$my_array=array();

if (mysqli_num_rows($result) > 0) {
    // 输出每行数据
    while($row = mysqli_fetch_assoc($result)) {
        $my_array[]=$row["id"];
    }

    // 删除数组中的指定元素
    for($i=0;$i<count($my_array);$i++){
      unset($my_array[$i]);
    }

    // 更新数据库中的数据
    for($i=0;$i<count($my_array);$i++){
      $sql = "DELETE FROM MyGuests WHERE id=".$my_array[$i];
      mysqli_query($conn, $sql);
    }
} else {
    echo "0 结果";
}

mysqli_close($conn);
?>

Using the above method, you can easily synchronize part of the data in the PHP deleted array to the database. However, it should be noted that when deleting array elements, you must carefully consider and perform data backup to avoid irreparable consequences caused by misoperation.

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