如何正确优化mysql select语句

Question

I have a web page that is divided into different sections. Each section has to show different results. These results are gotten from the database. This is a sample data on SQLfiddle

http://sqlfiddle.com/#!9/ad98b/1

The following code is what comes to my mind but I'm afraid that it might somehow overload the server when this page is accessed multiple times by different people

$sectionA = $connect->query("SELECT * FROM Main_Section WHERE section = `A` 
"); 
while ($row = $sectionA->fetch_array(MYSQLI_BOTH))
{
    $id = $row["id"];
    $name = $row["name"];
    $sec_result_a = $sec_result_a.'<p>'.$id.'</p><h3>'.$name.'</h3>';
}

$sectionB = $connect->query("SELECT * FROM Main_Section WHERE section = `B` "); 
while ($row = $sectionB->fetch_array(MYSQLI_BOTH))
{
    $id = $row["id"];
    $name = $row["name"];
    $sec_result_b = $sec_result_b.'<p>'.$id.'</p><h3>'.$name.'</h3>';
}

$sectionC = $connect->query("SELECT * FROM Main_Section WHERE section = `C` "); 
while ($row = $sectionC->fetch_array(MYSQLI_BOTH))
{
    $id = $row["id"];
    $name = $row["name"];
    $sec_result_c= $sec_result_c.'<p>'.$id.'</p><h3>'.$name.'</h3>';
}

UP TO section Z

Is there a way I can Optimise this properly?

Answer 1

Unless there's more to the picture, why not just query everything, ordered by section, to have the AZ:

SELECT * FROM Main_Section ORDER BY section

... and then process the results with one loop, which could look something like this:

$sections = $connect->query("SELECT * FROM Main_Section ORDER BY section"); 

while ($row = $sections->fetch_array())
{
    echo $row['section'] . ' ' . '<p>' . $row['id'] . '</p><h3>' . $row['firstname'] . ' ' . $row['lastname'] . '</h3>'; 
}