'CRUD application create working, but not update or delete
I tried getting the CRUD app to work from Tutorial Republic. I can create rows, but can’t read, update, or delete them.
I uploaded index, create, read, update, delete, config, and error.php. It loads index.php fine but when I try to update, read, or delete, all I get is a blank page. Please help. Here’s the code.
config.php
<?php
/* Database credentials. Assuming you are running MySQL
server with default setting (user 'root' with no password) */
define('DB_SERVER', 'localhost');
define('DB_USERNAME', 'user');
define('DB_PASSWORD', 'secret');
define('DB_NAME', 'demo');
/* Attempt to connect to MySQL database */
$link = mysqli_connect(DB_SERVER, DB_USERNAME, DB_PASSWORD, DB_NAME);
// Check connection
if($link === false){
die("ERROR: Could not connect. " . mysqli_connect_error());
}
?>
read.php
<?php
// Check existence of id parameter before processing further
if(isset($_GET["id"]) && !empty(trim($_GET["id"]))){
// Include config file
require_once "config.php";
// Prepare a select statement
$sql = "SELECT * FROM employees WHERE id = ?";
if($stmt = mysqli_prepare($link, $sql)){
// Bind variables to the prepared statement as parameters
mysqli_stmt_bind_param($stmt, "i", $param_id);
// Set parameters
$param_id = trim($_GET["id"]);
// Attempt to execute the prepared statement
if(mysqli_stmt_execute($stmt)){
$result = mysqli_stmt_get_result($stmt);
if(mysqli_num_rows($result) == 1){
/* Fetch result row as an associative array. Since the result set
contains only one row, we don't need to use while loop */
$row = mysqli_fetch_array($result, MYSQLI_ASSOC);
// Retrieve individual field value
$name = $row["name"];
$address = $row["address"];
$salary = $row["salary"];
} else{
// URL doesn't contain valid id parameter. Redirect to error page
header("location: error.php");
exit();
}
} else{
echo "Oops! Something went wrong. Please try again later.";
}
}
// Close statement
mysqli_stmt_close($stmt);
// Close connection
mysqli_close($link);
} else{
// URL doesn't contain id parameter. Redirect to error page
header("location: error.php");
exit();
}
?>
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>View Record</title>
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.5.2/css/bootstrap.min.css">
<style>
.wrapper{
width: 600px;
margin: 0 auto;
}
</style>
</head>
<body>
<div class="wrapper">
<div class="container-fluid">
<div class="row">
<div class="col-md-12">
<h1 class="mt-5 mb-3">View Record</h1>
<div class="form-group">
<label>Name</label>
<p><b><?php echo $row["name"]; ?></b></p>
</div>
<div class="form-group">
<label>Address</label>
<p><b><?php echo $row["address"]; ?></b></p>
</div>
<div class="form-group">
<label>Salary</label>
<p><b><?php echo $row["salary"]; ?></b></p>
</div>
<p><a href="index.php" class="btn btn-primary">Back</a></p>
</div>
</div>
</div>
</div>
</body>
</html>
update.php
<?php
// Include config file
require_once "config.php";
// Define variables and initialize with empty values
$name = $address = $salary = "";
$name_err = $address_err = $salary_err = "";
// Processing form data when form is submitted
if(isset($_POST["id"]) && !empty($_POST["id"])){
// Get hidden input value
$id = $_POST["id"];
// Validate name
$input_name = trim($_POST["name"]);
if(empty($input_name)){
$name_err = "Please enter a name.";
} elseif(!filter_var($input_name, FILTER_VALIDATE_REGEXP, array("options"=>array("regexp"=>"/^[a-zA-Z\s]+$/")))){
$name_err = "Please enter a valid name.";
} else{
$name = $input_name;
}
// Validate address address
$input_address = trim($_POST["address"]);
if(empty($input_address)){
$address_err = "Please enter an address.";
} else{
$address = $input_address;
}
// Validate salary
$input_salary = trim($_POST["salary"]);
if(empty($input_salary)){
$salary_err = "Please enter the salary amount.";
} elseif(!ctype_digit($input_salary)){
$salary_err = "Please enter a positive integer value.";
} else{
$salary = $input_salary;
}
// Check input errors before inserting in database
if(empty($name_err) && empty($address_err) && empty($salary_err)){
// Prepare an update statement
$sql = "UPDATE employees SET name=?, address=?, salary=? WHERE id=?";
if($stmt = mysqli_prepare($link, $sql)){
// Bind variables to the prepared statement as parameters
mysqli_stmt_bind_param($stmt, "sssi", $param_name, $param_address, $param_salary, $param_id);
// Set parameters
$param_name = $name;
$param_address = $address;
$param_salary = $salary;
$param_id = $id;
// Attempt to execute the prepared statement
if(mysqli_stmt_execute($stmt)){
// Records updated successfully. Redirect to landing page
header("location: index.php");
exit();
} else{
echo "Oops! Something went wrong. Please try again later.";
}
}
// Close statement
mysqli_stmt_close($stmt);
}
// Close connection
mysqli_close($link);
} else{
// Check existence of id parameter before processing further
if(isset($_GET["id"]) && !empty(trim($_GET["id"]))){
// Get URL parameter
$id = trim($_GET["id"]);
// Prepare a select statement
$sql = "SELECT * FROM employees WHERE id = ?";
if($stmt = mysqli_prepare($link, $sql)){
// Bind variables to the prepared statement as parameters
mysqli_stmt_bind_param($stmt, "i", $param_id);
// Set parameters
$param_id = $id;
// Attempt to execute the prepared statement
if(mysqli_stmt_execute($stmt)){
$result = mysqli_stmt_get_result($stmt);
if(mysqli_num_rows($result) == 1){
/* Fetch result row as an associative array. Since the result set
contains only one row, we don't need to use while loop */
$row = mysqli_fetch_array($result, MYSQLI_ASSOC);
// Retrieve individual field value
$name = $row["name"];
$address = $row["address"];
$salary = $row["salary"];
} else{
// URL doesn't contain valid id. Redirect to error page
header("location: error.php");
exit();
}
} else{
echo "Oops! Something went wrong. Please try again later.";
}
}
// Close statement
mysqli_stmt_close($stmt);
// Close connection
mysqli_close($link);
} else{
// URL doesn't contain id parameter. Redirect to error page
header("location: error.php");
exit();
}
}
?>
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Update Record</title>
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.5.2/css/bootstrap.min.css">
<style>
.wrapper{
width: 600px;
margin: 0 auto;
}
</style>
</head>
<body>
<div class="wrapper">
<div class="container-fluid">
<div class="row">
<div class="col-md-12">
<h2 class="mt-5">Update Record</h2>
<p>Please edit the input values and submit to update the employee record.</p>
<form action="<?php echo htmlspecialchars(basename($_SERVER['REQUEST_URI'])); ?>" method="post">
<div class="form-group">
<label>Name</label>
<input type="text" name="name" class="form-control <?php echo (!empty($name_err)) ? 'is-invalid' : ''; ?>" value="<?php echo $name; ?>">
<span class="invalid-feedback"><?php echo $name_err;?></span>
</div>
<div class="form-group">
<label>Address</label>
<textarea name="address" class="form-control <?php echo (!empty($address_err)) ? 'is-invalid' : ''; ?>"><?php echo $address; ?></textarea>
<span class="invalid-feedback"><?php echo $address_err;?></span>
</div>
<div class="form-group">
<label>Salary</label>
<input type="text" name="salary" class="form-control <?php echo (!empty($salary_err)) ? 'is-invalid' : ''; ?>" value="<?php echo $salary; ?>">
<span class="invalid-feedback"><?php echo $salary_err;?></span>
</div>
<input type="hidden" name="id" value="<?php echo $id; ?>"/>
<input type="submit" class="btn btn-primary" value="Submit">
<a href="index.php" class="btn btn-secondary ml-2">Cancel</a>
</form>
</div>
</div>
</div>
</div>
</body>
</html>
delete.php
<?php
// Process delete operation after confirmation
if(isset($_POST["id"]) && !empty($_POST["id"])){
// Include config file
require_once "config.php";
// Prepare a delete statement
$sql = "DELETE FROM employees WHERE id = ?";
if($stmt = mysqli_prepare($link, $sql)){
// Bind variables to the prepared statement as parameters
mysqli_stmt_bind_param($stmt, "i", $param_id);
// Set parameters
$param_id = trim($_POST["id"]);
// Attempt to execute the prepared statement
if(mysqli_stmt_execute($stmt)){
// Records deleted successfully. Redirect to landing page
header("location: index.php");
exit();
} else{
echo "Oops! Something went wrong. Please try again later.";
}
}
// Close statement
mysqli_stmt_close($stmt);
// Close connection
mysqli_close($link);
} else{
// Check existence of id parameter
if(empty(trim($_GET["id"]))){
// URL doesn't contain id parameter. Redirect to error page
header("location: error.php");
exit();
}
}
?>
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Delete Record</title>
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.5.2/css/bootstrap.min.css">
<style>
.wrapper{
width: 600px;
margin: 0 auto;
}
</style>
</head>
<body>
<div class="wrapper">
<div class="container-fluid">
<div class="row">
<div class="col-md-12">
<h2 class="mt-5 mb-3">Delete Record</h2>
<form action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]); ?>" method="post">
<div class="alert alert-danger">
<input type="hidden" name="id" value="<?php echo trim($_GET["id"]); ?>"/>
<p>Are you sure you want to delete this employee record?</p>
<p>
<input type="submit" value="Yes" class="btn btn-danger">
<a href="index.php" class="btn btn-secondary">No</a>
</p>
</div>
</form>
</div>
</div>
</div>
</div>
</body>
</html>
error.php
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Error</title>
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.5.2/css/bootstrap.min.css">
<style>
.wrapper{
width: 600px;
margin: 0 auto;
}
</style>
</head>
<body>
<div class="wrapper">
<div class="container-fluid">
<div class="row">
<div class="col-md-12">
<h2 class="mt-5 mb-3">Invalid Request</h2>
<div class="alert alert-danger">Sorry, you've made an invalid request. Please <a href="index.php" class="alert-link">go back</a> and try again.</div>
</div>
</div>
</div>
</div>
</body>
</html>
Sources
This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.
Source: Stack Overflow
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