获取多个表MySQL，加入

Question

I would like to select some information I have stored in my MySQL DB. For example I have 2 tables gameTable and playerTable. Now I want to get the gameTable and get the names and levels of these players. How do I do this??

This is what i got so far, it works but I'm not sure this is the most efficient way. Do I need to create a join for every reffered row??

<?php

include ('connect.php');


 $result = mysqli_query($connect,  
        "SELECT gameTable.id, 
            playerTable1.name AS name1, playerTable1.level AS level1, 
            playerTable2.name AS name2, playerTable2.level AS level2, 
            playerTable3.name AS name3, playerTable3.level AS level3, 
            playerTable4.name AS name4, playerTable4.level AS level4
         FROM gameTable
            JOIN playerTable AS playerTable1 ON gameTable.P1_id = playerTable1.id
            JOIN playerTable AS playerTable2 ON gameTable.P2_id = playerTable2.id
            JOIN playerTable AS playerTable3 ON gameTable.P3_id = playerTable3.id
            JOIN playerTable AS playerTable4 ON gameTable.P4_id = playerTable4.id
        ");

    while ($record = mysqli_fetch_array($result))
    { 
        echo $record['id']  . " - " 
            . $record['name1'] . " - " . $record['level1'] . " - " 
            . $record['name2'] . " - " . $record['level2'] . " - " 
            . $record['name3'] . " - " . $record['level3'] . " - " 
            . $record['name4'] . " - " . $record['level4'] . "<br>";
    }

?>

A second question, my database is set to MyISAM. Would it be helpful to change it to InnoDB? Or is this only useful for update delete etc. In your database and not for fetching data?

Answer 1

I would do it like this with the string(in reference to the comment question, not to the original question). This reserves just one string space for each location in memory. This saves the overhead of keeping assigning values for the intermediate strings and should save memory and even make execution time faster because string concatenation is a dreadfully slow processs at times.

$myarr = array();
 while ($record = mysqli_fetch_array($result))
  { 
    $myarr[] = $record['id'] ; 
    $myarr[] = " - " ;
    $myarr[] = $record['name1'] ;
    $myarr[] = " - " ;
    $myarr[] = $record['level1'];
    $myarr[] = " - ";
    $myarr[] = $record['name2'];
    $myarr[] = " - ";
    $myarr[] = $record['level2'];
    $myarr[] = " - ";
    $myarr[] = $record['name3'];
    $myarr[] = " - ";
    $myarr[] = $record['level3'];
    $myarr[] = " - ";
    $myarr[] = $record['name4'];
    $myarr[] = " - ";
    $myarr[] = $record['level4'];
    $myarr[] = "<br>";
 }
 echo implode('',$myarr);
 unset($myarr);