What are the potential pitfalls of using DISTINCT in SQL queries for PHP applications?

Using DISTINCT in SQL queries can impact performance as it requires the database to scan the entire result set to eliminate duplicates. In PHP applications, it is important to carefully consider if using DISTINCT is necessary and if there are alternative ways to achieve the desired results without using it. One way to avoid using DISTINCT is to properly structure your database schema and queries to avoid duplicate data entries. 

// Example of avoiding DISTINCT in SQL queries by properly structuring the database schema and queries

// Query to fetch unique user IDs
$query = "SELECT user_id FROM users";

// Fetching results and processing them
$result = $conn->query($query);
if ($result->num_rows > 0) {
    while($row = $result->fetch_assoc()) {
        // Process each unique user ID
    }
}

Keywords

SQL DISTINCT queries PHP applications performance

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