Glimpse SQL显示经常选择前2名

Question

参见本例

现在我不做前2，我只是做一个简单的实体查找，所以我有点不知道为什么。

Answer 1

您很可能使用SingleOrDefault或Find。这些方法通过选择前两行来工作。然后确保只返回一行。如果返回了多个元素，那么它将抛出异常。

如果有多场比赛，怎么知道？

// If there were two Products with a ProductName of Widget then the code would throw an exception.
context.Products.SingleOrDefault(i => i.ProductName == "Widget");

// If there were two Products with a ProductId of 1234 then the code would throw an exception.
context.Products.Find(1234);