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This article mainly explains "what are the problems with the use of ADO.NET components". The content in the article is simple and clear, and it is easy to learn and understand. Please follow the editor's train of thought to study and learn "what are the problems with the use of ADO.NET components".

After we get the DataReader object generated by the Command object executing the ExecuteReader method, we can extract and use the data in the record. DataReader doesn't get any data back at first, so call the Read method to ask DataReader to read out a piece of data first.

In the above code, reader.GetValue (I) is equivalent to reader [I] or reader [reader.GetName (I)], except that GetValue can access data only through indexes, while the latter can access data through both key values and indexes.

Because DataReader restricts reading one record at a time when reading data, using DataReader for ADO.NET components is not only resource-saving but also efficient. In addition to being more efficient in using DataReader objects, you can reduce the load on the network because you don't have to pass all the data back.

DataAdapter object and its use

The DataAdapter object mainly performs the data transfer between the Connection object and the DataSet object, and the ADO.NET component is structured on the Command object. DataAdapter executes SQL commands on the data source through the Command object, populates the data into the DataSet object, and returns data updates in the DataSet object to the data source.

Common methods for ADO.NET components:

(1) Update: updates the data in the data source based on the data stored in DataSet.

(2) Fill: populate or refresh DataSet with data from the data source, and the return value is the number of rows loaded into DataSet. The ADO.NET component method populates the DataSet with the results of the SelectCommand of the DataAdapter object.

Common properties of the DataAdapter object:

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(1) SelectCommand: retrieves data from a data source.

(2) InsertCommand: inserts data into the data source.

(3) DeleteCommand: delete data from the data source.

(4) UpdateCommand: update the data in the data source.

Use DataAdapter objects for data update operations

If there have been changes in DataSet, in this case, it would be a better choice for ADO.NET components to use DataAdapter's Update method to write local data changes back to the data source

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