C How to understand the data adapter in C

1. A data adapter is an integral part of a managed provider, a set of objects that communicate between a data source and a dataset. (In addition to adapters, managed providers include connection objects, data reader objects, and command objects.) Adapters are used to exchange data between data sources and datasets.

In many applications, this means reading data from a database into a dataset and then writing changed data back to the database from the dataset. However, data adapters can move data between arbitrary sources and datasets.

2,string querystring =select customerid, companyname from ";

sqldataadapter adapter = new sqldataadapter(querystring, connection);

dataset customers = new dataset();

customers");

The following connection is for MSDN regarding the data adapter.

It is a bridge between a data source and a data set.

The dataset gets the data through the adapter and becomes an in-memory data model that is disconnected from the try. It plays an intermediary role, flexible and convenient.

Generally speaking, the adapter is a bridge to connect to the database, and the database can be accessed through the adapter, making it easier to call the data of the database.

To put it bluntly, it's a class that Microsoft wrote for us, and we only need to call one of its methods to get data from the database. Don't worry about anything else. Convenient.

I don't understand at all, what is the "command type of the data adapter"?

Is it the relationship between sqldataadapter and sqlcommand in it?

What data adapter are you referring to? sqldataadapter?

Create an SQLDATAadapter object, call the fill(dataset dataset) method, and load the data in the database into local memory through the adapter.

To be specific, what adapter?

The purpose of the dataadapter is to facilitate the filling of data into the dataset, which is equivalent to automatically generating a data structure or class.

Used to store the data you get from querying the database.

This way you don't have to write a class based on the criteria of the query every time.

In situations that require a large amount of data processing or dynamic data interaction processes, adapters can be used to complete the interaction between the database and the native dataset in a connectionless manner.