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This article mainly introduces the DAO.NET DataSet object example analysis, has a certain reference value, interested friends can refer to, I hope you can learn a lot after reading this article, the following let the editor take you to understand it.

1. Overview of dataset DataSet

A dataset DataSet is a cache of data that can be used when it is disconnected from the data source in memory. As mentioned earlier in section 4-1-3 disconnected database access connections, you can think of the dataset DataSet as a database in memory. It is very powerful in supporting data in the application. Once DataSet is created, it can act as a database in the application, providing data support for the application.

The data structure of the dataset DataSet can be accomplished through wizards in the. net development environment, or you can add tables, data columns, constraints, and relationships between tables through code. The data in the dataset DataSet can either come from the data source or add rows to the table directly through code. It can also be seen that the dataset DataSet is similar to a client-side database in memory, where you can add and delete data tables, define the relationship between data table structure and tables, and add and delete rows in the table.

Dataset DataSet does not consider whether the table structure and data in it come from a database, XML file, or program code, so dataset DataSet does not maintain a connection to the data source. This relieves the pressure on database servers and networks. The characteristics of the dataset DataSet can be summarized as follows:

*, using the dataset object DataSet does not require direct interaction with the database

Second, DataSet objects are objects that store data retrieved from the database

Third, a DataSet object is a collection of zero or more table objects that consist of data rows and columns, constraints, and information about data relationships in the table

Fourth, DataSet objects can hold both database data and non-database data sources.

The structure, common properties and methods of 2.DataSet

The dataset DataSet exists as a DataSet object. The DAO.NET DataSet object is a user object that represents a set of related tables that are referenced as a unit in the application. The common properties of DataSet objects are Tables, Relations, and so on. The hierarchy diagram of the DataSet object shows:

The DataSet object consists of data tables and table relationships, so the DataSet object contains the DataTable object collection Tables and the DataRelation object collection Relations. Each data table contains rows and columns as well as constraints, so the DataTable object contains the DataRow object collection Rows, the DataColumn object collection Columns and the Constraint object collection Constraints. The classes in the DataSet hierarchy are shown in the table:

Class

Description

DataTableCollection

All DataTable objects that contain a specific dataset

DataTable

Represents a table in a dataset

DataColumnCollection

Represents the structure of a DataTable object

DataRowCollection

Represents the actual rows of data in the DataTable object

DataColumn

Represents the structure of columns in a DataTable object

DataRow

Represents a row of data in a DataTable object

Class description

DataTableCollection contains all DataTable objects for a specific dataset

DataTable represents a table in a dataset

DataColumnCollection represents the structure of the DataTable object

DataRowCollection represents the actual rows of data in the DataTable object

DataColumn represents the structure of columns in a DataTable object

DataRow represents a row of data in a DataTable object

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