Why is it recommended to avoid using SELECT * in SQL queries and instead specify the columns needed?

Using SELECT * in SQL queries can be inefficient and can lead to performance issues. It retrieves all columns from a table, even if not all columns are needed, which can result in unnecessary data transfer and processing. It's recommended to specify the columns needed in the SELECT statement to improve query performance and reduce the amount of data retrieved. 

// Specify the columns needed in the SQL query instead of using SELECT *
$sql = "SELECT column1, column2, column3 FROM table_name";
$result = mysqli_query($connection, $sql);

// Fetch and process the results as needed
while($row = mysqli_fetch_assoc($result)) {
    // Process the data
}

Keywords

PHP SQL SELECT * columns performance

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