mysql查询到三个表，想用JOIN代替子查询

Question

我想用join而不是子查询来查找trade_log上不存在的交易ID，通过下面的mysql语法的ip和当前日期过滤。

SELECT plug.id as a, 
     plug.url as b, 
     trade.id as c 
    FROM plug, trade 
WHERE trade.id = plug.trade_id 
    AND trade.id NOT IN (SELECT trade_log.trade_id 
          FROM trade_log 
         WHERE trade_log.ip = '".$ip."' 
          AND trade_log.log_date = CURDATE()) 
    AND trade.status = 1  
    AND plug.status = 1 
ORDER BY plug.weight DESC 
    LIMIT 1 

请帮我...

Answer 1

用途：

SELECT p.id as a, 
      p.url as b, 
      t.id as c 
    FROM PLUG p 
    JOIN TRADE t ON t.id = p.trade_id 
       AND t.status = 1 
LEFT JOIN TRADE_LOG tl ON tl.trade_id = t.id 
         AND tl.ip = mysql_real_escape_string($ip) 
         AND tl.log_date = CURDATE() 
    WHERE p.status = 1 
     AND tl.ip IS NULL 
ORDER BY p.weight DESC 
    LIMIT 1 

Answer 2

同OMG小马：

SELECT p.id as a, 
p.url as b, 
t.id as c 
FROM plug p 
INNER JOIN trade t ON (t.id = p.trade_id AND t.status = 1) 
LEFT JOIN trade_log l ON (l.trade_id = t.id AND l.ip = '".$ip."' AND l.log_date = CURDATE()) 
WHERE p.status = 1 AND l.trade_id IS NULL 
ORDER BY p.weight DESC 
LIMIT 1