How to convert query to array in php

In PHP programming, querying the database is a very common operation, and the need to convert query results into an array is equally common. PHP has many built-in functions to facilitate querying and array conversion. This article will introduce you to several common methods to help you better handle queries and array conversion in PHP.

1. Use the mysqli_fetch_array function to convert the query results into an associative array

The mysqli_fetch_array function can convert the query results into an associative array, and at the same time, array elements can be accessed as numeric subscripts. The specific usage of this function is as follows:

$result = mysqli_query( $conn, $query );
while ( $row = mysqli_fetch_array( $result, MYSQLI_ASSOC ) ) {
    // 处理查询结果
}

Among them, $conn is the mysqli object connected to the database, and $query is the query statement. Using the mysqli_fetch_array function in a while loop can obtain one row of query results each time and convert it into an associative array, and access the array elements through $row['attribute name'].

2. Use the mysqli_fetch_all function to convert the query results into a two-dimensional array

The mysqli_fetch_all function can convert the query results into a two-dimensional array. This function saves all query results in an array at one time. The specific usage is as follows:

$result = mysqli_query( $conn, $query );
$all_rows = mysqli_fetch_all( $result, MYSQLI_ASSOC );
foreach ( $all_rows as $row ) {
    // 处理查询结果
}

Among them, $conn is the mysqli object connected to the database, and $query is the query statement. After using the mysqli_fetch_all function, the $all_rows variable becomes a two-dimensional array, and the array elements can be accessed through a double loop.

3. Use the PDO query method to convert the query results into an associative array

The PDO query method can also convert the query results into an associative array. The specific method is as follows:

$pdo = new PDO( $dsn, $user, $password );
$stmt = $pdo->query( $query );
$rows = $stmt->fetchAll( PDO::FETCH_ASSOC );
foreach ( $rows as $row ) {
    // 处理查询结果
}

Among them, $dsn is the DSN string used to connect to the database, $user and $password are the username and password used to connect to the database. In a PDO query, use the fetchAll method to convert the query results into an associative array, and then access the array elements through a foreach loop.

4. Use the array_column function to extract column information from a two-dimensional array

Sometimes, we need to quickly extract a certain column of information from a two-dimensional array, and we can use the array_column function. The specific usage of this function is as follows:

$rows = array(
    array( 'id' => 1, 'name' => '张三', 'age' => 20 ),
    array( 'id' => 2, 'name' => '李四', 'age' => 22 ),
    array( 'id' => 3, 'name' => '王五', 'age' => 26 )
);
$names = array_column( $rows, 'name' );
print_r( $names );

In this example, we have a two-dimensional array $rows, which contains the id, name and age information of each person. Through the array_column function, we extract a new array $names from $rows, which only contains the name information of each person.

The above are several commonly used query and array conversion methods. In actual programming, we can choose the method that suits us best according to our needs. I wish you all better results in PHP programming!

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