MySQL UNION - 檢測幾個SELECT返回結果

Question

我有兩個SELECT查詢與UNION合併。這裏是MySQL的查詢：

SELECT `id`,`type`,`text` 
    FROM my_table 
WHERE position = '1' 
    AND status = '1' 
    AND targeting = 'all' 
UNION 
SELECT `id`,`type`,`text` 
    FROM my_table 
WHERE position = '1' 
    AND status = '1' 
    AND targeting LIKE '%US%' 

我怎樣才能找出這兩個SELECT查詢執行TRUE爲了從所需的行中獲取結果？

Answer 1

您可以根據查詢的哪個部分添加一個額外的列到你的查詢，返回不同的常數成功：

SELECT 'query1' AS `src`, `id`, `type`, `text` 
FROM my_table 
WHERE position = '1' AND status = '1' AND targeting = 'all' 

UNION ALL 

SELECT 'query2' AS `src`, `id`, `type`, `text` 
FROM my_table 
WHERE position = '1' AND status = '1' AND targeting LIKE '%US%' 

此外，在這種情況下，你不需要UNION都：

SELECT 
    targeting LIKE '%US%' AS `targeting_like_us`, 
    targeting = 'all' AS `targeting_equals_all`, 
    `id`, 
    `type`, 
    `text` 
FROM my_table 
WHERE position = '1' 
AND status = '1' 
AND (targeting LIKE '%US%' OR targeting = 'all')