試圖結合三個表基於我的情況MySQL的PHP​​？

Question

我想連接三個表。輸出將如下所示：在table_1上首先獲得水果價格4，並且在table_2上排除任何帶有mark 6的水果，然後在table_3上排除水果因素匹配的果實，然後獲取val的值，如果不是，我仍然保持Val值爲NULL的水果。我正在考慮加入，但不太確定如何結合三張桌子來做我想做的事情。幫助，欣賞。

<?php 
/* 
table_1 
fruit price 
apple 4 
banana 5 
pear 4 

table_2 
fruit mark 
apple 5 
banana 4 
pear  6 

table_3 
fruit factor val 
apple 56  good 
banana 89  good 
pear  56  bad 
*/ 
$sql = $wpdb->get_results($wpdb->prepare(" 
SELECT a.fruit, b.fruit, c.fruit, c.val 
FROM table_1 a, table_2 b, table_3 c WHERE a.price = %d AND b.fruit NOT IN 
(SELECT fruit FROM table_2 WHERE mark =%d) AND c.fruit = a.fruit OR c.factor = %d 
      ",$price,$mark,%factor)); 

foreach($sql as $sqls){ 
    $result1 = $sqls-> a.fruit; 
    $result2 = $sqls-> c.val;    
    $result[] = array($result1=>$result2); 
      } 

?> 

Answer 1

SELECT 
a.fruit,b.mark,c.factor,c.value 
from table_1 a, 
left join table_2 b 
on b.fruit=a.fruit and b.mark != 6 
left join table_3 c 
on c.fruit=a.fruit