What are the potential pitfalls of using mysql_num_rows to count unique entries in a column?

Using mysql_num_rows to count unique entries in a column may not give accurate results if there are duplicate values in the column. To accurately count unique entries, you should use a SQL query with the DISTINCT keyword to retrieve only distinct values from the column. 

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

// Query to count unique entries in a column
$query = "SELECT COUNT(DISTINCT column_name) as count FROM table_name";
$result = mysqli_query($connection, $query);

// Fetch the result
$row = mysqli_fetch_assoc($result);
$count = $row['count'];

// Output the count of unique entries
echo "Count of unique entries: " . $count;

// Close the connection
mysqli_close($connection);

Keywords

mysql_num_rows unique entries column count pitfalls

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