What are the potential pitfalls of using the max() function in a MySQL query?

Using the max() function in a MySQL query can potentially return unexpected results if the data being compared contains NULL values. To avoid this issue, you can use the COALESCE() function to replace NULL values with a specified default value before applying the max() function. 

$query = "SELECT MAX(COALESCE(column_name, default_value)) AS max_value FROM table_name";
$result = mysqli_query($connection, $query);

if($result){
    $row = mysqli_fetch_assoc($result);
    $maxValue = $row['max_value'];
    echo "The maximum value is: " . $maxValue;
} else {
    echo "Error: " . mysqli_error($connection);
}

Keywords

max function MySQL query data type conversion null values performance impact

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