DbParameter IsNullable 功能？

发布于 2024-07-26 20:58:53 字数 606 浏览 8 评论 0原文

我很少使用 ADO.Net 中的参数。我正在编写一个自定义 .Net 数据提供程序（以 SqlClient 为模型），并且必须在继承自 DbParameter 的参数类中实现 IsNullable 属性。我的数据提供程序不支持存储过程，因此我仅支持输入（替换样式）参数。

MSDN 文档对 IsNullable 的功能相当不清楚，指出“获取或设置一个指示参数是否接受空值的值”。谷歌搜索发现很多人对 IsNullable 的作用感到困惑，他们说将 IsNullable 设置为 false 并不会阻止他们使用空值参数，正如他们所期望的那样。

基于此，我认为 IsNullable 属性可能与存储过程的使用有关，以及存储过程的参数是否可为空，而不是参数值是否可以为空。

在这种情况下，由于我不会有存储过程，所以我的实现可以是：

        public override bool IsNullable { get { return false; } set {} }

为了避免必须摆弄一些测试代码来查看 SqlParameter 的 IsNullable 实现如何工作，如果有人有使用编写代码的经验，我将不胜感激参数可以解释 IsNullable。

原文

I have not worked with parameters in ADO.Net very much. I'm writing a custom .Net data provider (modeled on SqlClient), and have to implement the IsNullable property in my parameter class, which inherits from DbParameter. My data provider will not support stored procedures, so I will only be supporting Input (substitution style) parameters.

The MSDN docs are rather unclear on the functionality of IsNullable, stating "Gets or sets a value that indicates whether the parameter accepts null values." Googling turns up a lot of people confused about what IsNullable does, saying that setting IsNullable to false does not prohibit them from using a parameter will a null value, as they would have expected.

Based on this, I am thinking that perhaps the IsNullable property pertains to usage with a stored procedure, and whether or not the stored procedure's parameter is nullable, not whether the parameter value can be null.

In that case, since I won't have stored procedures, my implementation can just be:

        public override bool IsNullable { get { return false; } set {} }

To avoid having to fiddle around with some test code to see how SqlParameter's implementation of IsNullable works, I'd appreciate it if someone experienced in writing code using parameters could explain IsNullable.

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