MySQL查詢列出不屬於某種類型的項目

Question

我正在嘗試獲取我們的數據庫中的公司列表，它們是account_level IN ('basic', 'full')。我們的客戶是account_level ='enterprise'。在很多情況下，企業客戶端在db中也會有行，因爲他們基本或完整，所以我想排除也有企業行的任何基本/完整公司（即我想排除我們當前的客戶端）。通過這種方式，我可以得到一份嚴格基礎或全面的公司名單，但實際上並非我們的客戶。

這裏是該公司表的例子：

1 company a basic 
2 company a full 
3 company b basic 
4 company b enterprise 
5 company c basic 

我想查詢返回公司a和c。

我試圖使用方法：

SELECT * 
    FROM company c1 
    INNER JOIN company c2 ON c1.id=c2.id 
    WHERE c1.company NOT IN (SELECT c2.company FROM company c2  
    WHERE account_level = 'enterprise') 
    AND c1.account_level IN ('full', 'basic') 
    ORDER BY c1.company; 

，但沒有結果。有人可以看到我做錯了嗎？對不起，我還沒有經驗豐富的MySQL。謝謝你的幫助。

Answer 1

可以使用的EXISTS和NOT EXISTS組合得到期望的結果：

SELECT DISTINCT c1.company 
FROM company c1 
WHERE EXISTS (SELECT 1 
       FROM company AS c2 
       WHERE c1.company = c2.company AND c2.account_level IN ('full', 'basic')) 

     AND 

     NOT EXISTS (SELECT 1 
        FROM company AS c3 
        WHERE c1.company = c3.company AND c3.account_level IN ('enterprise') 

甚至更​​簡單：

SELECT DISTINCT c1.company 
FROM company c1 
WHERE c1.account_level IN ('full', 'basic')) 

     AND 

     NOT EXISTS (SELECT 1 
        FROM company AS c2 
        WHERE c1.company = c2.company AND c2.account_level IN ('enterprise')