需要SQL，提供只提供電腦和卡車的供應商名稱列表

Question

我有一個表名稱測試兩列，即：「供應商名稱」和「產品名稱」。現在我想要只在「卡車」和「計算機」中處理的供應商名稱。如下所示，該查詢的結果應僅返回「Ajit」。 儘管Gaurav在'卡車'和'電腦'中也進行交易，但他也在'BC'進行交易，所以查詢結果應該只返回供應商名稱作爲Ajit！

測試：

**SuppliarName**  **Product Name** 
Gaurav    Truck 
Ajit    Computer 
Rahul    Jhadu 
Gaurav    Computer 
Gaurav    BC 
Ajit    Truck 

Answer 1

我不會回答這個問題之前，OP會顯示他的努力，但對自我jarlh評論加入，不存在相信我可以證明這是可能的，只有這兩個選項中的一個：

自左連接：

SELECT DISTINCT t1.SuppliarName 
FROM Tbl t1 
LEFT JOIN Tbl t2 ON(t1.SuppliarName = t2.SuppliarName 
        AND t2.ProductName NOT IN('Truck', 'Computer')) 
WHERE t1.ProductName IN('Truck', 'Computer') 
AND t2.SuppliarName IS NULL; 

不存在：

SELECT DISTINCT t1.SuppliarName 
FROM Tbl t1 
WHERE t1.ProductName IN('Truck', 'Computer') 
AND NOT EXISTS(
    SELECT 1 
    FROM Tbl t2 
    WHERE t1.SuppliarName = t2.SuppliarName 
    AND t2.ProductName NOT IN('Truck', 'Computer') 
) 

see fiddle here.

更新我可能誤解了這個問題。如果要求是用於計算機和卡車由供應商來賣的話，三自聯接或自聯接與不存在將這樣的伎倆：

三重自聯接：

SELECT DISTINCT t1.SuppliarName 
FROM Tbl t1 
INNER JOIN Tbl t2 ON(t1.SuppliarName = t2.SuppliarName 
        AND t1.ProductName <> t2.ProductName) 
LEFT JOIN Tbl t3 ON(t1.SuppliarName = t3.SuppliarName 
        AND t3.ProductName NOT IN('Truck', 'Computer')) 
WHERE t1.ProductName ='Truck' 
AND t2.ProductName = 'Computer' 
AND t3.SuppliarName IS NULL; 

自聯接與不存在：

SELECT DISTINCT t1.SuppliarName 
FROM Tbl t1 
INNER JOIN Tbl t2 ON(t1.SuppliarName = t2.SuppliarName 
        AND t1.ProductName <> t2.ProductName) 
WHERE t1.ProductName ='Truck' 
AND t2.ProductName = 'Computer' 
AND NOT EXISTS (
    SELECT 1 
    FROM tbl t3 
    WHERE t3.SuppliarName = t1.SuppliarName 
    AND t3.ProductName NOT IN('Truck', 'Computer') 
) 

see fiddle here.

Answer 2

SELECT * FROM dbo.Table1 t1 
WHERE EXISTS (SELECT * FROM dbo.Table1 t2 
       WHERE t1.SuppliarName = t2.SuppliarName 
       AND t2.[Product Name] = 'Computer') 
AND EXISTS (SELECT * FROM dbo.Table1 t3 
       WHERE t1.SuppliarName = t3.SuppliarName 
       AND t3.[Product Name] = 'Truck') 
AND NOT EXISTS (SELECT * FROM dbo.Table1 t4 
       WHERE t1.SuppliarName = t4.SuppliarName 
       AND t4.[Product Name] NOT IN ('Computer', 'Truck')) 

http://sqlfiddle.com/#!6/fc6f9/1