在w3schools這題 https://bit.ly/2D7WLmn 範例中
SELECT SupplierName
FROM Suppliers
WHERE EXISTS (SELECT ProductName FROM Products
WHERE Products.SupplierID = Suppliers.supplierID AND Price < 20);
會得到 24 個 SupplierName的結果
但是如果我改寫成
SELECT SupplierName
FROM Suppliers
WHERE EXISTS (SELECT ProductName FROM Products,suppliers
WHERE Products.SupplierID = Suppliers.supplierID AND Price < 20);
會得到 29 個 SupplierName的結果
多出來的五筆資料Price都 > 20
不知道兩個SQL語法的差別在哪裡，懇請大大指導