PHP Introduction - Lecture #19

PHP - DATABASE CONNECTIVITY Contd.

Hello All... welcome every one. I'm going to start PHP lectures for Very Beginners, who wants to learn PHP from very beginning. No matter if you do not have any basic programming concept. If you follow my tutorials I hope you will surely get some how good knowledge of PHP.

Today our Topic is

PHP-DATABASE

Today we will learn about how to fetch record from MySQL and display on browser using SELECT query. As told earlier before performing any action with MySQL you need connection with MySQL at the top of coding even before of HTML coding.

<?php

$conn = mysqli_connect(“localhost”, “root”, “”, “school”) OR die(mysqli_connect_error($conn));

?>

After you have successful connection with MySQL you need to retrieve data from MySQL. How you will retrieve here is the process.

<?php

            $qry = mysqli_query($conn, "SELECT * FROM students");

            if($qry){

                        while($row = mysqli_fetch_array($qry)){

                                    echo $row['student_id'];

                                    echo $row['student_name'];

                                    echo $row['student_address'];

            }

            }

?>

Here is the simple changing after the query is true. After the query is true we have started a while loop and inside that while loop we have given a function mysqli_fetch_array() that will retrieve the information from table and it takes parameter the query above you have initialized and that is stored in a variable called `row` or anything you want. Now the record has been retrieved we just need to echo/display it on browser and to display. Little changing while displaying record we need to echo column names as defined in MySQL table within the brackets and single quotations, along with the variable name in which mysqli_fetch_array is stored. Below is the pictorial view of code and retrieval of records.

I have used <br /> tag to more clarify the records otherwise it may be difficult to understand. Why there has been used While loop not any other because if you remember in previous lectures of loop that While loop works on basis of condition, and if there is no records in table and mysqli_fetch_array will return nothing and 0 will be stored to row variable and 0 means nothing or false. And if while loop becomes 0 or false it will not work further. Further DIE function is used in the connection coding that if connection is not established or not connected properly `OR` statement will be executed, DIE function is used to stop the execution of code, if there is any error in connection only error will be shown on browser no remaining code will be executed not even HTML code.

Thanks Guys. Any thing missing or any question from this topic you can comment below, I will be trying to solve and answer your question.

Our topic continues to `PHP-DATABASE`

Good Luck J