SELECT A.month,ifnull(B.count,0) AS count FROM(SELECT '1月' AS `month` UNION SELECT '2月' AS `month` UNION SELECT '3月' AS `month` UNION SELECT '4月' AS `month` UNION SELECT '5月' AS `month` UNION SELECT '6月' AS `month` UNION SELECT '7月' AS `month` UNION SELECT '8月' AS `month` UNION SELECT '9月' AS `month` UNION SELECT '10月' AS `month` UNION SELECT '11月' AS `month` UNION SELECT '12月' AS `month` ) AS A LEFT JOIN (SELECT CONCAT(MONTH(SBSJ),'月') AS month, COUNT(*) AS COUNT FROM cg_khdb_khxq WHERE YEAR(SBSJ) = 2023 GROUP BY MONTH ORDER BY MONTH)B ON A.month = B.month，优化一下这条sql

可以尝试使用临时表和子查询来优化这个 SQL。具体做法如下：

CREATE TEMPORARY TABLE IF NOT EXISTS months (
  month VARCHAR(10) NOT NULL,
  PRIMARY KEY (month)
);

INSERT INTO months (month)
VALUES
  ('1月'), ('2月'), ('3月'), ('4月'), ('5月'), ('6月'),
  ('7月'), ('8月'), ('9月'), ('10月'), ('11月'), ('12月');

SELECT
  months.month,
  IFNULL(B.count, 0) AS count
FROM
  months
  LEFT JOIN (
    SELECT
      CONCAT(MONTH(SBSJ), '月') AS month,
      COUNT(*) AS count
    FROM
      cg_khdb_khxq
    WHERE
      YEAR(SBSJ) = 2023
    GROUP BY
      MONTH
    ORDER BY
      MONTH
  ) AS B ON months.month = B.month;

这个 SQL 使用了一个临时表 `months`，其中包含了所有的月份信息。然后使用左连接将其与子查询的结果进行关联，最终得到了所有月份对应的客户需求数量。这种做法可以避免使用 `UNION` 操作，从而提高查询效率。

相关问题

select c.area_name,c.mon,c.count,ifnull(c1.count1,0),ifnull(c1.count1,0)/count * 100 from ( select a.area_name,MONTH(pb.wlpb_create_time) mon,count(pb.id) count from bc_company_info b inner join ( select b.id from wk_ledger_produce_gather g left join bc_company_info b on b.id =g.bci_id where g.wlpg_year =2022 group by b.id HAVING sum(g.wlpg_total_produce) >=30 UNION select b.id from wk_plan_info p left join wk_plan_danger d on d.wpi_id = p.id left join bc_company_info b on b.id = p.bci_id where p.wpi_year = 2022 group by b.id HAVING sum(d.wpd_this_produce) >30) b1 on b1.id = b.id left join wk_ledger_produce_bill pb on pb.bci_id = b.id left join sys_area a on a.id = b.bci_city where pb.wlpb_create_time >'2023-01-01 00:00:00' group by b.bci_city,MONTH(pb.wlpb_create_time) ) c left join ( select a.area_name,MONTH(pb.wlpb_create_time) mon,count(pb.id) count1 from bc_company_info b inner join ( select b.id from wk_ledger_produce_gather g left join bc_company_info b on b.id = g.bci_id where g.wlpg_year =2022 group by b.id HAVING sum(g.wlpg_total_produce) >=30 UNION select b.id from wk_plan_info p left join wk_plan_danger d on d.wpi_id = p.id left join bc_company_info b on b.id = p.bci_id where p.wpi_year = 2022 group by b.id HAVING sum(d.wpd_this_produce) >30) b1 on b1.id = b.id left join wk_ledger_produce_bill pb on pb.bci_id = b.id left join sys_area a on a.id = b.bci_city where pb.wldb_end_from != 1 and pb.wlpb_create_time >'2023-01-01 00:00:00' group by b.bci_city,MONTH(pb.wlpb_create_time)) c1 on c.area_name = c1.area_name and c.mon = c1.mon 这段SQL怎么优化

这段SQL语句比较复杂，可以考虑以下几个方面进行优化：

1. 索引优化：根据EXPLAIN命令的查询计划，确定哪些表需要添加索引，可以在表的关键字段上添加索引，提高查询效率。

2. 减少子查询：可以将子查询中的重复代码提取出来，避免多次重复查询。另外，可以考虑使用临时表或者表变量等方式，将子查询的结果存储在临时表中，然后再进行关联查询，避免多次重复查询。

3. 减少ifnull函数的使用：可以使用LEFT JOIN或者COALESCE函数代替ifnull函数，避免多次重复计算。

4. 确认需要查询的字段：可以根据实际需要，确认需要查询的字段，并且避免查询不必要的字段，提高查询效率。

总之，优化复杂SQL语句需要综合考虑多个方面，并且需要根据具体情况进行调整，从而提高查询效率。

SET @end_date = '2023-03-31'; SET @start_date = DATE_ADD(@end_date + INTERVAL 1 DAY, INTERVAL -12 MONTH); SET @last_end_date = LAST_DAY(DATE_ADD(@end_date , INTERVAL -12 MONTH)); SET @last_start_date = DATE_ADD(@end_date + INTERVAL 1 DAY, INTERVAL -24 MONTH); #1.近一年所有店铺gmv相关数据; SELECT 购买渠道, ifnull(支付年月,'时间合计') AS 支付年月, ifnull(子品牌,'子品牌合计') AS 子品牌, COUNT(DISTINCT 用户id) AS 购买人数, SUM(商品实付金额) AS 购买金额, SUM(商品实付金额) / COUNT(DISTINCT 用户id) AS 客单价 FROM valid_order WHERE 支付日期 BETWEEN @start_date AND @end_date GROUP BY 1,2,3 WITH ROLLUP #与上半部分区别是月份和子品牌顺序调换，主要是因为合计人数会因为去重逻辑不同而产生差异 UNION ALL SELECT 购买渠道, null AS 支付年月, COALESCE(子品牌,'子品牌合计') AS 子品牌, COUNT(DISTINCT 用户id) AS 购买人数, SUM(商品实付金额) AS 购买金额, SUM(商品实付金额) / COUNT(DISTINCT 用户id) AS 客单价 FROM valid_order WHERE 支付日期 BETWEEN @start_date AND @end_date GROUP BY 1,2,3;优化代码

可以尝试以下几点优化：

1. 使用变量代替函数计算，例如将 `LAST_DAY` 函数替换为 `DATE_FORMAT(DATE_ADD(@end_date , INTERVAL -12 MONTH), '%Y-%m-31')`。

2. 将条件筛选放在子查询中进行，以减少 `valid_order` 表中的数据量。例如：

   SELECT 购买渠道, ifnull(支付年月,'时间合计') AS 支付年月, ifnull(子品牌,'子品牌合计') AS 子品牌, COUNT(DISTINCT 用户id) AS 购买人数, SUM(商品实付金额) AS 购买金额, SUM(商品实付金额) / COUNT(DISTINCT 用户id) AS 客单价 
   FROM ( 
       SELECT * 
       FROM valid_order 
       WHERE 支付日期 BETWEEN @start_date AND @end_date 
   ) t 
   GROUP BY 1,2,3 WITH ROLLUP 

3. 将多个查询语句合并为单个查询，使用 `UNION ALL` 进行拼接。

   SELECT 购买渠道, ifnull(支付年月,'时间合计') AS 支付年月, ifnull(子品牌,'子品牌合计') AS 子品牌, COUNT(DISTINCT 用户id) AS 购买人数, SUM(商品实付金额) AS 购买金额, SUM(商品实付金额) / COUNT(DISTINCT 用户id) AS 客单价 
   FROM ( 
       SELECT * 
       FROM valid_order 
       WHERE 支付日期 BETWEEN @start_date AND @end_date 
   ) t 
   GROUP BY 1,2,3 WITH ROLLUP 
   UNION ALL 
   SELECT 购买渠道, null AS 支付年月, COALESCE(子品牌,'子品牌合计') AS 子品牌, COUNT(DISTINCT 用户id) AS 购买人数, SUM(商品实付金额) AS 购买金额, SUM(商品实付金额) / COUNT(DISTINCT 用户id) AS 客单价 
   FROM ( 
       SELECT * 
       FROM valid_order 
       WHERE 支付日期 BETWEEN @start_date AND @end_date 
   ) t 
   GROUP BY 1,2,3;