What is the best way to avoid duplicate entries when retrieving data from a MySQL table in PHP?

When retrieving data from a MySQL table in PHP, one way to avoid duplicate entries is to use the DISTINCT keyword in your SQL query. This will ensure that only unique rows are returned. Another approach is to use the GROUP BY clause to group the results by a specific column, which can also help eliminate duplicates. Additionally, you can use PHP to filter out duplicate entries by storing the retrieved data in an array and checking for duplicates before displaying or processing it. 

// Connect to MySQL database
$connection = mysqli_connect("localhost", "username", "password", "database");

// Query to retrieve data with DISTINCT keyword
$query = "SELECT DISTINCT column_name FROM table_name";
$result = mysqli_query($connection, $query);

// Loop through results and display data
while ($row = mysqli_fetch_assoc($result)) {
    echo $row['column_name'] . "<br>";
}

// Close database connection
mysqli_close($connection);

Keywords

PHP MySQL duplicate entries data retrieval unique constraint

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