何时使用ExecuteScalar，ExecuteReader和ExecuteNonQuery？ [英] When to use ExecuteScalar, ExecuteReader, and ExecuteNonQuery?

问题描述

我对

I am confused with the usage of

1. ExecuteScalar


2. ExecuteReader
$的用法感到困惑在我的代码中执行SQL查询时，b $ b
3. ExecuteNonQuery

1. ExecuteScalar
2. ExecuteReader
3. ExecuteNonQuery

什么时候应该使用这些方法？

when executing SQL queries in my code. When should I use each of these methods?

推荐答案

• ExecuteScalar（） 仅返回查询第一行第一列中的值。


• ExecuteReader（）返回一个对象，该对象可以遍历整个结果集，而一次只在内存中保留一条记录。


• ExecuteNonQuery（）完全不返回数据：仅受插入，更新或删除影响的行数。


• ExecuteScalar() only returns the value from the first column of the first row of your query.
• ExecuteReader() returns an object that can iterate over the entire result set while only keeping one record in memory at a time.
• ExecuteNonQuery() does not return data at all: only the number of rows affected by an insert, update, or delete.

此外，您还可以查看 DbDataAdapter 类型，其中包括 Fill（）方法，使您可以将整个结果集下载到 DataTable 或 DataSet 对象，以及许多其他功能。

Additionally, you can look at the DbDataAdapter type, which includes a Fill() method that allows you to download the entire resultset into a DataTable or DataSet object, as well as a number of other abilities.

最后，这似乎是您获取的好时机熟悉 Microsoft文档。这就是为之准备的文档：您拥有方法名称；去查一下。

Finally, this seems like a good time for you to get familiar with Microsoft Docs. This is what documentation is made for: you have the method names; go look them up.

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