MySQL的 - 從結果

Question

選擇我有一個表

scores(user, score) 

，我有這個疑問

SET @row_num = 0; 
SELECT @row_num := @row_num + 1 as row_index, user, score 
FROM scores ORDER BY score DESC 

現在我要選擇，從這個查詢結果，與名的用戶「約翰」和得分'1400'知道他的row_index是什麼，像

SELECT row_index 
FROM *result* WHERE user='john' AND score=1400 

我該怎麼做？我試圖

SET @row_num = 0; 
SELECT row_index 
FROM (SELECT @row_num := @row_num + 1 as row_index, user, score 
     FROM scores ORDER BY score DESC)  
WHERE user='john' AND score=1400` 

但phpMyAdmin的說

#1248 - Every derived table must have its own alias 

我怎麼能這樣做？

謝謝 亞歷山德羅

Answer 1

你還沒有添加的別名派生表。

SELECT row_index FROM (...) AS alias 
WHERE alias.user = 'john' AND alias.score = 1400 

Answer 2

嘗試使用views。

SET @row_num = 0; 
CREATE VIEW v AS SELECT @row_num := @row_num + 1 as row_index, user, score FROM scores ORDER BY score DESC; 
SELECT row_index FROM v; 

Answer 3

查詢：

SET @row_num = 0; 
SELECT a.row_index 
FROM (SELECT @row_num := @row_num + 1 as row_index, 
      user, 
      score 
      FROM scores) a 
WHERE a.user='john' AND a.score=1400 
ORDER BY a.score DESC 

我覺得子查詢訂購併不總是被允許的。

Answer 4

試試這個：

SET @row_num = 0; 

SELECT row_index FROM (SELECT @row_num := @row_num + 1 as row_index, user, 
score FROM scores ORDER BY score DESC) AS alias1 WHERE user='john' AND score=1400