將三個MySQL查詢結果爲一個結果排序正確

Question

我有表，它的查詢結果，我需要通過下列標準命令：

1）排名的100或更大的價值（排序最高到最低）

2）List_Date - 最近90天內最近到最早的日期。

3）排名的值小於100（排序最高到最低）

我嘗試以下，但意識到它不會按照MySQL的文檔工作，「因爲UNION默認產生一組無序的行「。

(SELECT Ranking, List_Date 
FROM example_table 
WHERE Ranking > 100 
ORDER BY Ranking DESC) 

UNION 

(SELECT Ranking, List_Date 
FROM example_table 
WHERE List_Date BETWEEN CURDATE() - INTERVAL 90 DAY AND CURDATE() 
ORDER BY List_Date DESC) 

UNION 

(SELECT Ranking, List_Date 
FROM example_table 
WHERE Ranking < 100 
ORDER BY Ranking DESC) 

我想找出如何保持順序沿三條語句。可能？

Answer 1

看起來您不需要使用UNION作爲您的條件可以使用OR合併。試試這個：

SELECT Ranking, List_Date 
FROM example_table 
WHERE Ranking <> 100 
OR List_Date BETWEEN CURDATE() - INTERVAL 90 DAY AND CURDATE() 
ORDER BY Ranking, List_Date DESC 

Answer 2

我假設你真正需要的UNION因爲在其他的答案提到的例子可以沒有它來解決，通常它會影響性能。你可以把它全部包裝在一個新的SELECT聲明中。

SELECT * FROM (
(SELECT Ranking, List_Date 
FROM example_table 
WHERE Ranking > 100 
ORDER BY Ranking DESC) 

UNION 

(SELECT Ranking, List_Date 
FROM example_table 
WHERE List_Date BETWEEN CURDATE() - INTERVAL 90 DAY AND CURDATE() 
ORDER BY List_Date DESC) 

UNION 

(SELECT Ranking, List_Date 
FROM example_table 
WHERE Ranking < 100 
ORDER BY Ranking DESC) 

) AS NEW_TEMP 
ORDER BY NEW_TEMP.Ranking, NEW_TEMP.List_Date DESC 

Answer 3

好，而我收到的答覆並沒有直接解決我的問題，他們指出我在正確的方向。這是我的解決方案。它有效，但可能不雅緻。

SELECT * FROM (
(SELECT (@cnt := @cnt + 1) AS rowNumber, Ranking, List_Date 
FROM example_table 
CROSS JOIN (SELECT @cnt := 0) AS dummy 
WHERE Ranking > 100 
ORDER BY Ranking DESC) 

UNION 

(SELECT (@cnt := @cnt + 1) AS rowNumber, Ranking, List_Date 
FROM example_table 
CROSS JOIN (SELECT @cnt := (SELECT COUNT(*) FROM `example_table `)) AS dummy 
WHERE List_Date BETWEEN CURDATE() - INTERVAL 90 DAY AND CURDATE() 
ORDER BY List_Date DESC) 

UNION 

(SELECT (@cnt := @cnt + 1) AS rowNumber, Ranking, List_Date 
FROM example_table 
CROSS JOIN (SELECT @cnt := ((SELECT COUNT(*) FROM `example_table `) * 2)) AS dummy 
WHERE Ranking < 100 
ORDER BY Ranking DESC) 
) as T 
ORDER BY rowNumber DESC