僅當它們符合某些條件時才從另一個表插入表值

Question

我試圖在MySQL中創建以下僞代碼。我有以下表格：

• 特價
• product_filter

的product_filter表只有兩列，product_id和filter_id

我想拿出一個SQL是：

1. 從中讀取所有的product_id表，並把它們放入product_filter表
2. 當從specials表中讀取的產品ID，就需要看price柱太
3. 如果價格在$ 100，過濾器ID是1
4. 如果價格爲$ 100和$ 500之間，過濾器ID將是2
5. 如果價格爲$ 500和$ 1000，過濾器ID是3

這是我到目前爲止有：

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

任何幫助表示讚賞。

Answer 1

試試這個，使用CASE確定filter_id是什麼（這將設置任何不具有等於0的邊界的價格） ：

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; 

這裏有一個工作SQLFiddle。

Answer 2

試試這個查詢（你沒有指定高於1000的值，所以如果值大於1000，它會使filter_id 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

使用這樣的事情：

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

試試這個：

您還需要如下條款範圍內的值之間的細微變化：

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;