php - 将 3 个 mysql 查询合并为 1 个

Question

我需要查询两个新表 $res_info 和 $res_text...如何将所有 3 个查询合并为一个。第一个查询 $res 获取所有内容，包括在其他两个表中使用的唯一字段 m_id。这可以通过UNION来完成吗？

$res = @mysql_query("SELECT *, DATE_FORMAT(m_lld,'%m/%d/%y') 
                    AS m_lld_formatted 
                    FROM social_members
                    WHERE m_user='$en[user]'");

if (@mysql_num_rows($res) == 0) call404();
$line = @mysql_fetch_assoc($res);
foreach ($line as $key => $value) 
        $en['m'.$key] = str_replace("\n",'<br/>',stripslashes($value));

$res_info = mysql_query("SELECT *, 
                            FROM social_meminfo 
                            WHERE m_id = '".$en['mm_id']."'");
$res_text = mysql_query("SELECT *, 
                            FROM social_memtext 
                            WHERE m_id = '".$en['mm_id']."'");

Answer 1

根据您的评论，我认为您正在寻找一个 OUTER JOIN 和另一个 INNER JOIN，如下所示:

SELECT sm.*, DATE_FORMAT(sm.m_lld,'%m/%d/%y') AS m_lld_formatted 
FROM social_members sm
LEFT OUTER JOIN social_memtext smt ON (sm.m_id = smt.m_id)
JOIN social_meminfo smi ON (sm.m_id = smi.m_id)
WHERE sm.m_user = "$en['user']"

LEFT OUTER JOIN 将处理表 social_memtext 确实有匹配条目的情况。