SQL IN（）無法正常工作

Question

這是我的查詢，但顯示的結果是錯誤的。

SELECT winner 
FROM nobel 
WHERE 
    subject = 'Economics' AND 
    yr IN (
    SELECT min('yr') 
    FROM nobel 
    WHERE subject = 'Economics' 
); 

Answer 1

我相信這個問題是包裹yr的MIN()，這使得優化器地址裏給出的報價爲這會導致它被評價爲MIN(constant_value)這始終是constant_value一個字符串。

嘗試：

SELECT winner FROM nobel 
WHERE subject='Economics' 
     AND yr IN (SELECT min(yr) FROM nobel WHERE subject='Economics'); 

Answer 2

的問題是圍繞yr單引號作爲@sagi指出。我只是想指出的是，一個相關的條款是這樣的查詢與=一起比較典型的：

SELECT n.winner 
FROM nobel n 
WHERE n.subject = 'Economics' AND 
     n.yr = (SELECT min(yr) FROM nobel n2 WHERE n2.subject = n.subject); 

採用=與in這裏看起來像一個小點給你。但是，=表示最多返回一行，in表示可能返回多行。這是SQL優化器的一個重要區別。

Answer 3

SELECT winner 
FROM nobel 
WHERE 
    subject = 'Economics' AND 
    yr IN (
     SELECT min(yr) # ---> just remove quotes in your query, it will work 
     FROM nobel 
     WHERE subject = 'Economics' 
    );