What Type of Data Will Fetchall() Return?
When working with databases in web development, it’s important to understand how to retrieve data from a database using SQL queries. One commonly used method is
fetchall(). In this tutorial, we will explore what type of data the
fetchall() method returns and how to work with it.
fetchall() method is used to fetch all the rows returned by an SQL query. It returns the result as a list of tuples, where each tuple represents a row of data.
<?php $query = "SELECT * FROM users"; $result = $pdo->query($query); $data = $result->fetchAll(); ?>
In the above example, we execute an SQL query to retrieve all the user records from a hypothetical “users” table. The
$result variable holds the result set, and the
$data variable stores the fetched data using the
The returned data is in the form of a list of tuples. Each tuple represents a row from the database table, and each element within a tuple represents a column value. For example, if our “users” table has columns like “id”, “name”, and “email”, each tuple will contain three elements corresponding to these columns.
Working with Returned Data:
- To access specific elements within a tuple, we can use array indexing. For example,
$datawill give us the value of the second column in the first row.
- We can also iterate over the list of tuples using a loop to access each row of data individually.
fetchall() method is a powerful tool for retrieving data from a database using SQL queries. It returns the result as a list of tuples, which allows for easy manipulation and access to individual elements. By understanding the format of the returned data and how to work with it, you can effectively retrieve and utilize data in your web applications.