How to modify array database in php

PHP language is often used to manipulate data in web development, including arrays and databases. This article will introduce some common methods for modifying array databases.

1. Array

In PHP language, array is one of the most commonly used data types. An array can store multiple values, and each value in it can be accessed through an index.

1.1 Create an array

There are two ways to create an array, namely using the array() function and using square brackets [].

Use the array() function to create an array. You can add a series of values ​​in parentheses. Each value has a corresponding index and can be accessed through the index. For example:

$array = array('foo'=>'bar', 'baz'=>'qux','123'=>'456');

Use square brackets [] to create an array, and you can specify the key-value pairs in the array. For example:

$array = ['foo' => 'bar', 'baz' => 'qux', '123' => '456'];

In the above creation method, the keys are specified as strings in the first example, while in the second array creation method, the keys can also be specified using numbers.

1.2 Accessing array elements

Use the keys of the array to access the elements. You can use the square brackets [] operator. For example:

echo $array['foo']; //输出bar

In the above example, the value of the array element is accessed.

1.3 Modify array elements

To modify the element value of the array, you only need to specify the key, and then use the assignment symbol ‘=’ to set it to a new value. For example:

$array['foo'] = 'new bar';

Put square brackets [] after the variable name of the array, fill in the index of the element to be operated on in the brackets, and then assign the new value to it. If the key does not exist, a new element will be created.

1.4 Delete array elements

To delete array elements, you can use the unset() function, for example:

unset($array['foo']);

In the above example, $array['foo'] The 'foo' is the key of the array element.

2. Database

There are many databases commonly used in PHP, such as MySQL, SQLite, PostgreSQL, etc. Here I will take MySQL as an example to introduce how to use PHP to modify the data in the database.

2.1 Connect to the database

Before modifying the database data, you must first connect to the database. Connecting to the database can use MySQLi or PDO extensions.

Using the MySQLi extension, you can use the mysqli_connect() function to connect to the database:

$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());
}

Among them, $servername, $username and $password are the names of the MySQL servers used to connect to the database, respectively. Login username and password. $dbname specifies the name of the database to connect to.

2.2 Modify the data in the database

To modify the data in the database, you usually need to execute SQL statements.

For example, to change the name of a row in a data table named "test" to "newname", you can use the following SQL statement:

UPDATE test SET name='newname' WHERE id=1;

In PHP, you can use the mysqli_query() function to execute this SQL statement, as shown below:

$sql = "UPDATE test SET name='newname' WHERE id=1";

if (mysqli_query($conn, $sql)) {
    echo "数据修改成功";
} else {
    echo "错误: " . mysqli_error($conn);
}

Executing SQL statement, mysqli_query() returns a Boolean value indicating whether the operation was successful.

2.3 Close the database connection

After completing the operation on the database, you need to close the database connection to avoid unnecessary resource occupation.

Close the database connection is very simple, just execute the mysqli_close() function:

mysqli_close($conn)

3. Advantages and disadvantages of modifying array database with PHP

3.1 Advantages

• PHP is simple and fast to modify the array database, and is suitable for a large number of data operation needs.
• PHP modifies the array database and directly operates the array elements, which is convenient, free and flexible.
• PHP modifying the array database can process the data to be modified before operation, reducing server load and improving the operating efficiency of Web applications.

3.2 Disadvantages

• When PHP modifies the array database to process a large amount of data, it needs to connect to the database multiple times, which can easily cause load and affect performance.
• PHP cannot use the complete SQL statement syntax to modify the array database.
• PHP modifying the array database is not suitable for high-concurrency situations where the amount of data requested is large.

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