What are some potential issues with the PHP code provided for creating a statistic graph?

Issue: The provided PHP code does not include error handling for potential issues such as database connection errors or query failures. This can lead to unexpected behavior or blank graphs if the data retrieval fails. To solve this, we should add proper error handling to ensure that the graph is only generated when the data retrieval is successful. 

// Check for database connection errors
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}

// Perform the SQL query
$result = $conn->query($sql);

// Check for query execution errors
if (!$result) {
    die("Query failed: " . $conn->error);
}

// Proceed with generating the graph
// (code for generating the graph goes here)

Keywords

SQL injection data validation GD library error handling graph rendering

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