根據列值匹配的值插入值

Question

MySQL初學者在這裏。我有兩個表（如下所示），其中一個（頻率）我想根據數據與參考列（type_freq下面）匹配的列來插入值。例如，'rs9'（來自freqs）的類型爲「GG」，該'GG'值與type_freq表中的'type2'匹配，並且我想將相應的頻率（本例中爲'.2'）插入到頻率值爲'rs9'。

我試着玩弄案件陳述無濟於事。我是否認爲這最好通過幾個案例陳述來解決？有沒有更好的方法？我非常感謝任何反饋。謝謝！

---

表：

---

表freqs

rsid  type  freq 
rs9   GG 
rs8   CC 
rs1   CC 

表type_freq

rid  type1 type1_frequency type2 type2_frequency type3  type3_frequency 
rs9  AA  .7    GG  .2    GC   .1 
rs8  CC  .5    TT  .3    AT   .2 
rs1  AA  .9    CC  .1    .   . 

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我的代碼：

UPDATE freqs SET req = 
    (
(SELECT type1_Frequency CASE 
    WHEN type.freqs = type1.type_frequencies 
      FROM type_frequencies 
    END CASE) 
(SELECT type2_Frequency CASE 
    WHEN type.freqs = type2.type_frequncies 
      FROM type_frequencies 
    END CASE) 
(SELECT type3_Frequency CASE 
    WHEN type.freqs = type3.type_frequencies 
      FROM type_frequencies 
    END CASE) 
    ) 

Answer 1

首先，讓我們設計了創建您的type_freq表的規範化版本的查詢：

SELECT rid, type1 AS type, type1_frequency AS frequency 
FROM type_freq 
UNION ALL 
SELECT rid, type2 AS type, type2_frequency AS frequency 
FROM type_freq 
UNION ALL 
SELECT rid, type3 AS type, type3_frequency AS frequency 
FROM type_freq 

現在，讓我們使用這個更新表格：如果你有控制

UPDATE freqs 
SET freq = 
(
    SELECT frequency 
    FROM 
    (
     SELECT rid, type1 AS type, type1_frequency AS frequency 
     FROM type_freq 
     UNION ALL 
     SELECT rid, type2 AS type, type2_frequency AS frequency 
     FROM type_freq 
     UNION ALL 
     SELECT rid, type3 AS type, type3_frequency AS frequency 
     FROM type_freq 
    ) x 
    WHERE x.type = freqs.type AND x.rid = freqs.rsid 
) 

注在你的數據庫模式上，我會建議永久規範你的type_freq表。