如何選擇MAX SQL

Question

我已經形成了德比以下查詢來計算所有棒球運動員的安打率...

SELECT p1.nameFirst as "First", 
p1.nameLast as "Last", 
(b1.H + (2 * b1.doubles) + (3 * b1.triples) + (4 * b1.HR))/(b1.AB * 1.0) as "SLUGGING" 
FROM Batting b1 join Players p1 on b1.playerID = p1.playerID 
WHERE AB >= 400; 

它生產的所有打者誰在蝙蝠有400以上，並計算它們的猛擊的百分比。我的問題是，我只需要選擇一個最大塞流率的球員。我嘗試用SELECT MAX圍繞數學模塊，但無濟於事。我期望的輸出...

何塞·包蒂斯塔0.7426900584795321637426900

此外，有沒有什麼辦法來格式化小數到數字的設定金額是多少？任何建議表示讚賞。

Answer 1

將ORDER BY SLUGGING DESC LIMIT 1添加到您的查詢，你應該得到最好的結果。

編輯： 看來Derby不支持限制返回的行數。那麼最好的方法是創建一個帶有最大壓制效果的子查詢，並加入到獲得playerId來打印。

Answer 2

我開始懷疑我是否幫助你爲MBA寫作或做計算機科學作業。 :-)

SELECT 
    p1.nameFirst as "First", 
    p1.nameLast as "Last", 
    b.s AS "SLUGGING" 
FROM 
(
    SELECT 
     MAX(
      (b1.H + (2 * b1.doubles) + (3 * b1.triples) + (4 * b1.HR))/(b1.AB * 1.0) 
     ) AS s 
    FROM 
     Batting b1 
    WHERE 
     b1.AB >= 400 
) m1 
JOIN 
    Batting b 
     ON 
       m1.s = (b.H + (2 * b.doubles) + (3 * b.triples) + (4 * b.HR))/(b.AB * 1.0) 
JOIN 
    Players p1 
     ON 
      b1.playerID = p1.playerID 
WHERE 
    b1.AB >= 400 

OR

*不知道這是支持

SELECT 
    TOP 1 
    p1.nameFirst as "First" 
    , p1.nameLast as "Last" 
    , (b1.H + (2 * b1.doubles) + (3 * b1.triples) + (4 * b1.HR))/(b1.AB * 1.0) AS "SLUGGING" 
FROM 
    Batting b1 
JOIN 
    Players p1 on b1.playerID = p1.playerID 
WHERE 
    b1.AB >= 400 
ORDER BY 
    (b1.H + (2 * b1.doubles) + (3 * b1.triples) + (4 * b1.HR))/(b1.AB * 1.0) DESC 

OR

*我認爲，這將工作

SELECT * FROM (
SELECT 
    ROW_NUMBER() OVER(
     ORDER BY 
      (b1.H + (2 * b1.doubles) + (3 * b1.triples) + (4 * b1.HR))/(b1.AB * 1.0) DESC 
    ) as rownum 
    , p1.nameFirst as "First" 
    , p1.nameLast as "Last" 
    , (b1.H + (2 * b1.doubles) + (3 * b1.triples) + (4 * b1.HR))/(b1.AB * 1.0) AS "SLUGGING" 
FROM 
    Batting b1 
JOIN 
    Players p1 on b1.playerID = p1.playerID 
WHERE 
    b1.AB >= 400 
) AS r 
WHERE r.rownum = 1