忽略插入如果值为null

Question

所以我有查询，像这样：

INSERT INTO price_hist 
      ( 
         date, 
         product_id, 
         price_min, 
         price_max, 
         price_avg, 
         merchants 
      ) 
      VALUES 
      ( 
         '2015-07-10', 
         100388, 
         ( 
           SELECT min(price) 
           FROM prices 
           WHERE product_id = 100388 
           AND active = 1), 
         ( 
           SELECT max(price) 
           FROM prices 
           WHERE product_id = 100388 
           AND active = 1), 
         ( 
           SELECT avg(price) 
           FROM prices 
           WHERE product_id = 100388 
           AND active = 1), 
         ( 
           SELECT count(price) 
           FROM prices 
           WHERE product_id = 100388 
           AND active = 1) 
      ) 

price_max，price_min和price_avg不能为空，但并不是所有产品都涨价了，所以很自然的子查询这些产品返回NULL。如果我使用INSERT IGNORE，查询确实执行，但不是跳过插入，而是将0值插入所有这些字段。任何方式，我可以修改它，所以它会一起跳过插入，如果任何字段为空？

product_history表已经有设置的字段，所以它们不能为NULL。

Answer 1

只需使用一个INSERT ... SELECT，而不是：你的子查询的查询

INSERT INTO price_hist 
( 
    date, 
    product_id, 
    price_min, 
    price_max, 
    price_avg, 
    merchants 
) 
SELECT 
    '2015-07-10', 
    100388, 
    min(price), 
    max(price), 
    avg(price), 
    count(price) 
FROM prices 
WHERE product_id = 100388 
AND active = 1 
HAVING count(price) 

Answer 2

使用IFNULL()

试试这个

INSERT INTO price_hist 
     ( 
        date, 
        product_id, 
        price_min, 
        price_max, 
        price_avg, 
        merchants 
     ) 
     VALUES 
     ( 
        '2015-07-10', 
        100388, 
        ( 
          IFNULL(SELECT min(price) 
          FROM prices 
          WHERE product_id = 100388 
          AND active = 1), 0), 
        ( 
          IFNULL(SELECT max(price) 
          FROM prices 
          WHERE product_id = 100388 
          AND active = 1), 0), 
        ( 
          IFNULL(SELECT avg(price) 
          FROM prices 
          WHERE product_id = 100388 
          AND active = 1), 0), 
        ( 
          IFNULL(SELECT count(price) 
          FROM prices 
          WHERE product_id = 100388 
          AND active = 1), 0) 
     ) 

Answer 3

INSERT INTO price_hist 
      ( 
         date, 
         product_id, 
         price_min, 
         price_max, 
         price_avg, 
         merchants 
      ) 
      VALUES 
      ( 
         '2015-07-10', 
         100388, 
         ( 
           SELECT ifnull(min(price),0) 
           FROM prices 
           WHERE product_id = 100388 
           AND active = 1), 
         ( 
           SELECT max(price) 
           FROM prices 
           WHERE product_id = 100388 
           AND active = 1), 
         ( 
           SELECT ifnull(avg(price),0) 
           FROM prices 
           WHERE product_id = 100388 
           AND active = 1), 
         ( 
           SELECT count(price) 
           FROM prices 
           WHERE product_id = 100388 
           AND active = 1) 
      )