如何從MySQL表

得到最後和Secondlast記錄從上面的圖片，我有ň的記錄與號CAT_ID和sub_cat_id但在圖像只有兩個在那裏。

，所以我希望得到最後和secondlastscore_in_per值命名爲lastScore和latetsScore ..

我怎樣才能檢索..？

SELECT 
(SELECT score_in_per FROM tbl_student_skill_score ORDER BY date DESC LIMIT 2,0) as lastScore, 
(SELECT score_in_per FROM tbl_student_skill_score ORDER BY date DESC LIMIT 1) as latetsScore

我是新來這個複雜的MySQL logics..This我曾嘗試..

例子： 可以說，一個用戶的電子郵件是[email protected]採取相同的測試2時間和測試與一個類別和子類別相關聯。所以用戶會參加任何次數的測試...

從那條記錄我想得到最後兩個記錄的百分比。

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2017-04-22 Mr world wide

你的子查詢有什麼問題？你想要什麼結果？我看不到圈出來的行是最新的還是最新的。 –

它不工作，有時它說內部查詢得到多個值..現在latetsScore來了，但最後得分作爲'空' –

讓我解釋清楚有問題給一分鐘。 –

SELECT 
( SELECT score_in_per  FROM tbl_student_skill_score WHERE cat_id=1 and sub_cat_id=5 ORDER BY date,id DESC LIMIT 1) AS latestScore, 
( SELECT score_in_per  FROM tbl_student_skill_score WHERE cat_id=1 and sub_cat_id=5 ORDER BY date,id DESC LIMIT 1,1 ) AS lastScore

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2017-04-22 13:35:44

如果我理解正確;您想要選擇特定學生所進行的特定類型考試的兩個最新結果。

您不正確使用LIMIT子句。這是正確的語法：LIMIT {[offset,] row_count | row_count OFFSET offset}。另外，你完全忽略了where子句。

所以查詢應該是：

SELECT 
(SELECT score_in_per FROM tbl_student_skill_score 
    WHERE user_email = "email of the user you are interested in" 
    AND cat_id = categoryOfTestOfInterest 
    AND sub_cat_id = subcategoryOfTestOfInterest 
    ORDER BY date DESC LIMIT 1, 1 
)AS lastScore, 
(SELECT score_in_per FROM tbl_student_skill_score 
    WHERE user_email = "email of the user you are interested in" 
    AND cat_id = categoryOfTestOfInterest 
    AND sub_cat_id = subcategoryOfTestOfInterest 
    ORDER BY date DESC LIMIT 1 
)AS latetsScore;

如果一個學生可以參加IELTS考試在一天內多次（如圖像建議）應該比你還爲了通過ID（假定該ID總是更大新的結果），或者更好的是，僅由ID：

SELECT 
(SELECT score_in_per FROM tbl_student_skill_score 
    WHERE user_email = "email of the user you are interested in" 
    AND cat_id = categoryOfTestOfInterest 
    AND sub_cat_id = subcategoryOfTestOfInterest 
    ORDER BY id DESC LIMIT 1, 1 
)AS lastScore, 
(SELECT score_in_per FROM tbl_student_skill_score 
    WHERE user_email = "email of the user you are interested in" 
    AND cat_id = categoryOfTestOfInterest 
    AND sub_cat_id = subcategoryOfTestOfInterest 
    ORDER BY id DESC LIMIT 1 
)AS latetsScore;

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2017-04-22 13:42:45 Cerike

一個解決這個問題的方法是使用分區通過。
Step1：我已經按照分區的降序排列了不同的cat_id和sub_cat_id的數據。
第二步：我已經使用等級-1這是最新的分數，並與秩2合併，它是倒數第二個得分

with chck as 
(select 
    cat_id,sub_cat_id,score_in_per,date1, 
    row_number() over(partition by cat_id,sub_cat_id order by 
    cat_id,sub_cat_id,date1 desc) as row_num 
from tbl) 

    select a.*,b.second_last_score from 
    (select cat_id,sub_cat_id,score_in_per,date1,row_num as last_score from chck where row_num=1) a 
    left join 
    (select cat_id,sub_cat_id,score_in_per,date1,row_num as second_last_score from chck where row_num=2) b 
    on a.cat_id = b.cat_id and a.sub_cat_id = b.sub_cat_id;

讓我知道的任何查詢的情況。

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2017-04-22 14:52:21

如何從MySQL表

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