How to query data table and return array in php

When developing using PHP, it often involves querying the database. For the need to query the data table and return an array, we can use the database operation extension provided by PHP to achieve it. In this article, we will introduce in detail how to use PHP to query a data table and return an array. We hope it will be helpful to beginners.

1. Connect to the database

Before using PHP to operate the database, we first need to connect to the database. We can use the mysqli extension or PDO extension provided by PHP to achieve this. The following is a sample code for mysqli extension to connect to the MySQL database:

$servername = "localhost"; //数据库主机名
$username = "username"; //数据库用户名
$password = "password"; //数据库密码
$dbname = "myDB"; //数据库名

// 创建连接
$conn = mysqli_connect($servername, $username, $password, $dbname);

// 检测连接
if (!$conn) {
  die("Connection failed: " . mysqli_connect_error());
}

2. Query the data table and return the array

After successfully connecting to the database, we can use PHP to query the data table and return the array . The following is an example code for using mysqli extension to query a data table:

$sql = "SELECT * FROM myTable";
$result = mysqli_query($conn, $sql);

if (mysqli_num_rows($result) > 0) {
  // 输出数据
  $data = array(); // 定义一个数组存放数据
  while($row = mysqli_fetch_assoc($result)) {
    $data[] = $row; // 将每一行数据存入数组
  }
  print_r($data); // 输出数组
} else {
  echo "0 results";
}

The above code will query the data table named "myTable" and store the query results in the array $data. We can use the print_r() function to output the contents of the array $data. Note: When using the mysqli_fetch_assoc() function, you need to note that the function returns an associative array by default. For index arrays, you need to use the mysqli_fetch_row() function.

3. Close the database connection

After we complete all database query operations, we need to close the database connection. The following is a sample code for closing the database connection using the mysqli extension:

mysqli_close($conn);

With the above code, we can successfully close the database connection.

Summary:

When using PHP to query a data table and return an array, you need to pay attention to the following points:

1. Use mysqli extension or PDO extension to connect to the database;
2. When querying the data table, you need to use the mysqli_query() function or PDO's query() function;
3. Use the mysqli_fetch_assoc() function or PDO's fetch() function to obtain data from the result set;
4. Save each row of data into an array, and finally output the array.

As long as we follow the above steps, we can easily implement the function of querying the data table and returning an array. At the same time, we also need to pay attention to ensuring the security of the code to avoid injection attacks in SQL statements. When performing SQL operations, it is best to use security methods such as parameterized queries to ensure the security and reliability of the code.

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