Question

我在mysql查询中创建了一个UNION。这对我来说很好。

此查询的主要目的是从多个表中获取通知的数据。

这需要0.0009 sec次执行。数据较少。

任何sql专家都可以帮我改进这个SQL查询或引导我进行这个SQL查询。

I am not good in mysql

  SELECT
        HM_notification.product_id,
        HM_products.slug,
        HM_notification.action_type,
        HM_notification.url,
        HM_notification.read_date
        FROM `HM_notification` 
            JOIN HM_customers ON HM_customers.id = HM_notification.added_by 
            JOIN HM_products ON HM_products.id = HM_notification.product_id 
            JOIN HM_reviews ON HM_reviews.product_id = HM_notification.product_id 
            WHERE HM_products.user_id=34 AND HM_notification.added_by != 34 AND action_type = 'reviews'

    UNION        

  SELECT 
        HM_notification.product_id,
        HM_products.slug,
        HM_notification.action_type,
        HM_notification.url,
        HM_notification.read_date
        FROM `HM_notification` 
            JOIN HM_customers ON HM_customers.id = HM_notification.added_by 
            JOIN HM_bid ON HM_bid.product_id = HM_notification.product_id 
            JOIN HM_products ON HM_products.id = HM_notification.product_id 
            WHERE HM_products.user_id=34 AND HM_notification.added_by != 34  AND action_type = 'newbid' OR action_type = 'editbid'

    UNION        

    SELECT 
        HM_notification.product_id,
        HM_products.slug,
        HM_notification.action_type,
        HM_notification.url,
        HM_notification.read_date
        FROM `HM_notification` 
            JOIN HM_customers ON HM_customers.id = HM_notification.added_by 
            JOIN HM_products ON HM_products.id = HM_notification.product_id 
            JOIN HM_order_items ON HM_order_items.product_id = HM_notification.product_id 
            WHERE HM_products.user_id=34 AND HM_notification.added_by != 34 AND (action_type = 'order_pending' OR action_type = 'processing' OR action_type = 'onhold' OR action_type = 'unhold' OR action_type = 'receive' OR action_type = 'addshipment' OR action_type = 'editshipment' OR action_type = 'newcomment' OR action_type = 'addshipmentcomment')

    UNION        

  SELECT 
        HM_notification.product_id,
        HM_products.slug,
        HM_notification.action_type,
        HM_notification.url,
        HM_notification.read_date
        FROM `HM_notification` 
            JOIN HM_customers ON HM_customers.id = HM_notification.added_by 
            JOIN HM_products ON HM_products.id = HM_notification.product_id 
            JOIN HM_conversation ON HM_conversation.pid = HM_notification.product_id 
            WHERE HM_products.user_id=34 AND HM_notification.added_by != 34 AND (HM_conversation.user_one != 34 || HM_conversation.user_two != 34) AND action_type = 'conversation'

这是一个简单的SQL查询，用于获取具有产品ID的特定网址。

Answer 1

因为我没有看到你的桌子，我现在的想法是，你最好使用＆＃39; NATURAL JOIN＆＃39;而不是加入＆＃39;如果可能的话，把你的条件放在＆＃39; WHERE＆＃39;部分查询。因为前者更快更聪明......

希望它有所帮助...

Answer 2

使用此查询。

   SELECT 
    n.product_id, 
    p.slug, 
    (case when (p.user_id=9 and n.action_type='product_review') then 'reviews' 
    when (n.action_type='bid_added') then p.slug 
    when (n.action_type='order_processing' OR n.action_type='order_shipped' OR n.action_type='order_onhold' OR n.action_type='order_unhold' OR n.action_type='received') then 'orderlist' 
    when ((con.user_one!=9 OR con.user_two!=9) and n.action_type='chat') then 'messages' end) HM_url
     from HM_notification n, 
          HM_customers c, 
          HM_products p, 
          HM_reviews r, 
          HM_bid b, 
          HM_order_items o, 
          HM_conversation con 
     where  
        n.added_by=c.id 
        and p.id=n.product_id 
        and r.product_id=n.product_id 
        and b.product_id=n.product_id 
        and o.product_id=n.product_id 
        and con.pid=n.product_id 
        and n.added_by != 9;

Answer 3

试试这个：

SELECT
            HM_notification.product_id,
            HM_products.slug,
            HM_notification.action_type,
            HM_notification.url,
            HM_notification.read_date
            FROM `HM_notification` 
                JOIN HM_customers ON HM_customers.id = HM_notification.added_by 
                JOIN HM_products ON HM_products.id = HM_notification.product_id 
                JOIN HM_reviews ON HM_reviews.product_id = HM_notification.product_id 
                WHERE HM_products.user_id=34 AND HM_notification.added_by != 34 AND action_type = 'reviews'

        UNION        

      SELECT 
            HM_notification.product_id,
            HM_products.slug,
            HM_notification.action_type,
            HM_notification.url,
            HM_notification.read_date
            FROM `HM_notification` 
                JOIN HM_customers ON HM_customers.id = HM_notification.added_by 
                JOIN HM_bid ON HM_bid.product_id = HM_notification.product_id 
                JOIN HM_products ON HM_products.id = HM_notification.product_id 
                WHERE HM_products.user_id=34 AND HM_notification.added_by != 34  AND (action_type = 'newbid' OR action_type = 'editbid')

        UNION        

        SELECT 
            HM_notification.product_id,
            HM_products.slug,
            HM_notification.action_type,
            HM_notification.url,
            HM_notification.read_date
            FROM `HM_notification` 
                JOIN HM_customers ON HM_customers.id = HM_notification.added_by 
                JOIN HM_products ON HM_products.id = HM_notification.product_id 
                JOIN HM_order_items ON HM_order_items.product_id = HM_notification.product_id 
                WHERE HM_products.user_id=34 AND HM_notification.added_by != 34 AND (action_type = 'order_pending' OR action_type = 'processing' OR action_type = 'onhold' OR action_type = 'unhold' OR action_type = 'receive' OR action_type = 'addshipment' OR action_type = 'editshipment' OR action_type = 'newcomment' OR action_type = 'addshipmentcomment')

        UNION        

      SELECT 
            HM_notification.product_id,
            HM_products.slug,
            HM_notification.action_type,
            HM_notification.url,
            HM_notification.read_date
            FROM `HM_notification` 
                JOIN HM_customers ON HM_customers.id = HM_notification.added_by 
                JOIN HM_products ON HM_products.id = HM_notification.product_id 
                JOIN HM_conversation ON HM_conversation.pid = HM_notification.product_id 
                WHERE HM_products.user_id=34 AND HM_notification.added_by != 34 AND (HM_conversation.user_one != 34 OR HM_conversation.user_two != 34) AND action_type = 'conversation'

使用多个表在mysql中连接的多个联合

3 个答案: