Question

我正在尝试在MySQL中创建以下伪代码。我有以下表格：

特别
product_filter

product_filter表只有两列，product_id和filter_id

我想提出一个SQL：

从specials表中读取所有product_id并将其放入product_filter表
从specials表中读取产品ID时，还需要查看price列
如果价格低于100美元，过滤器ID将为1
如果价格介于$ 100和$ 500之间，则过滤器ID为2
如果价格介于$ 500和$ 1000之间，则过滤器ID将为3

这是我到目前为止所做的：

INSERT INTO product_filter (product_id,filter_id)
SELECT product_id, 
FROM specials;

感谢任何帮助。

Answer 1

尝试使用CASE来确定filter_id是什么（这将设置在这些边界中没有价格等于0的任何内容）：

INSERT INTO product_filter (product_id,filter_id)
SELECT product_id,
    (CASE WHEN price < 100 then 1
    WHEN price >= 100 AND price < 500 then 2
    WHEN price >= 500 AND price < 1000 then 3
    ELSE 0 END) AS filter_id
FROM specials;

这是一个有效的SQLFiddle。

Answer 2

尝试此查询（您未指定高于1000的值，因此如果值大于1000，则会使filter_id为4。）

INSERT INTO product_filter (product_id,filter_id)
SELECT product_id,
       CASE WHEN price < 100 THEN 1
            WHEN price BETWEEN 100 AND 500 THEN 2
            WHEN price BETWEEN 500 AND 1000 THEN 3
            ELSE 4
       END as filter_id
FROM specials;

Answer 3

使用类似的东西：

INSERT INTO product_filter (product_id,filter_id)
SELECT
  product_id, 
  (CASE
       WHEN price < 100 THEN 1 
       WHEN price BETWEEN 100 AND 500 THEN 2
       WHEN price BETWEEN 500 AND 1000 THEN 3
   END) as filter_id
 FROM specials;

Answer 4

试试这个：

您还需要在子句范围值之间进行微小更改，如下所示：

INSERT INTO product_filter (product_id,filter_id)
SELECT product_id, 
       case when price < 100 then 1 -- price under $100, the filter id be 1
            -- price between $100 and $500, the filter id be 2
            when price between 101 and 500 then 2
            -- price between $500 and $1000, the filter id be 3
            when price between 501 and 1000 then 3
            -- else ? -- fill this as you need
FROM specials;

仅当满足特定条件时，才从另一个表中插入表值

4 个答案: