SQL - 过滤器值为空时全选
我的 ASP.net Web 应用程序中有一个 SQL 查询，如下所示:
I have a SQL query in my ASP.net web app that looks like this:
SELECT * FROM [Records] WHERE ([title] LIKE '%' + @title + '%')
@title，当然是页面上一个文本框的值.
@title, of course, is the value of a text box on the page.
我的问题是，为什么当文本框为空时，这不返回任何内容?我怎样才能让它返回一切，就像逻辑告诉我它应该那样?
My question is, why, when the text box is empty, does this return nothing? And how can I make it return everything, like logic tells me it ought to?
推荐答案
SELECT * FROM [Records]
WHERE @title IS NULL OR LEN(@Title) = 0 OR ([title] LIKE '%' + @title + '%')
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