How to add, update and delete data from MySQL database using PHP

1. PHP and MySQL connection

Before performing any operation, we need to first establish a PHP and MySQL connection. This can be achieved by using mysqli or PDO PHP extension. The following is a sample code using the mysqli extension:

<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDB";

$conn = mysqli_connect($servername, $username, $password, $dbname);

if (!$conn) {
    die("Connection failed: " . mysqli_connect_error());
}
echo "Connected successfully";
?>

In the above code, we created a connection variable named $conn, which contains the IP address, username of the MySQL server , password and database name. If the connection fails, an error message is output and script execution is terminated. If successful, "Connected successfully" will be output

2. Insert data from the database

If you want to save data into the MySQL database, you can use the INSERT INTO command. Here is a sample code to insert data into a table:

<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDB";

$conn = mysqli_connect($servername, $username, $password, $dbname);

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

$sql = "INSERT INTO myTable (firstname, lastname, email)
VALUES (&#39;John&#39;, &#39;Doe&#39;, &#39;john@example.com&#39;)";

if (mysqli_query($conn, $sql)) {
    echo "New record created successfully";
} else {
    echo "Error: " . $sql . "<br>" . mysqli_error($conn);
}

mysqli_close($conn);
?>

In the above code, we have created a SQL query variable named $sql which adds the data to In the table named myTable. If the execution is successful, "New record created successfully" is output, otherwise an error message is output.

3. Update data from the database

To update the data in the database, we can use the UPDATE statement. Here is an example of updating specific data:

<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDB";

$conn = mysqli_connect($servername, $username, $password, $dbname);

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

$sql = "UPDATE myTable SET lastname=&#39;Doe Jr.&#39; WHERE id=1";

if (mysqli_query($conn, $sql)) {
    echo "Record updated successfully";
} else {
    echo "Error updating record: " . mysqli_error($conn);
}

mysqli_close($conn);
?>

In the above code, we have created a SQL query variable named $sql which will update the lastname in the specified row Updated to "Doe Jr." If the execution is successful, "Record updated successfully" is output, otherwise an error message is output.

4. Delete data from the database

To delete data from the database, we can use the DELETE statement. Below is a sample code to delete a row from a table:

<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDB";

$conn = mysqli_connect($servername, $username, $password, $dbname);

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

$sql = "DELETE FROM myTable WHERE id=3";

if (mysqli_query($conn, $sql)) {
    echo "Record deleted successfully";
} else {
    echo "Error deleting record: " . mysqli_error($conn);
}

mysqli_close($conn);
?>

In the above code, we are using the SQL query variable named $sql to delete a specific row in the table. If the execution is successful, "Record deleted successfully" is output, otherwise an error message is output.

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