DbCommand参数集合缺少AddWithValue方法 [英] DbCommand Parameters collection missing AddWithValue method
问题描述
在xxxCommand类中的每个ADO.NET提供程序中，有很多"Add"的Parameters集合。方法之一是AddWithValue，接受参数的名称和参数的值。
使用不可知的DBCommand，只有Add方法和AddWithValue缺失。
你必须用factory.CreateParameter（）创建一个新的DbParameter然后设置参数名称和值。
为什么这个类中缺少这个有用的方法???
提前谢谢。
< p class = MsoNormal style ="margin：0cm 0cm 0pt"> 嗨delfo，
我使用反射器来查看DbParameterCollection和SqlParameterCollection的机制。
在SqlParameterCollection的AddWithValue方法中，它实际调用构造函数：
public SqlParameter AddWithValue（ string parameterName， object value）
{
返回 此 .Add（ n ew SqlParameter（parameterName，value））;
}
< span style ="font-size：10pt; font-family：'Verdana'，'sans-serif'"lang = EN-US>
所以它就像你在DbPrameter中做的一样。
并且SqlParameterCollection继承自DbParameterCollection。其他ParameterCollections也继承 形式。
在我的选择中，让父类更整洁更有利。当AddWithValue可以由构造函数完成时，虽然方便，但是不必在父类中添加它。但是，当涉及到子类时，对其他类的影响较小。
你可以从这个URL下载反射器：http://www.red-gate.com/products/reflector/
最好的问候
Yichun Feng
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Hi,
in every ADO.NET provider inside the xxxCommand class there's the Parameters collection that have a lot of "Add" method one of them is AddWithValue, that accept parameter's name and parameter's value.
Using the agnostic DBCommand, there's only the Add method and AddWithValue is missing.
You must create a new DbParameter with factory.CreateParameter() and than set Parameter name and value.
Why is this usefull method missing in this class ???
Thanks in advance.
Hi delfo,
I use reflector to look at the mechanism of DbParameterCollection and SqlParameterCollection.
In the SqlParameterCollection’s AddWithValue method, it calls the constructor actually:
public SqlParameter AddWithValue(string parameterName, object value)
{
return this.Add(new SqlParameter(parameterName, value));
}
So it just do the same thing as you do in DbPrameter.
And SqlParameterCollection inherits from DbParameterCollection. other ParameterCollections inherit form it too.
In my option, making the parent class neat is more favorable. When AddWithValue can be done by constructor, it is not very necessary to add it in the parent class although it is convenient. However, when it comes to child class, the effect to other classes is lower.
You can download reflector form this URL: http://www.red-gate.com/products/reflector/
Best Regards
Yichun Feng
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