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This article mainly explains "what are the types of ADO.NET data sets". The content of the explanation is simple and clear, and it is easy to learn and understand. Please follow the editor's ideas to study and learn "what are the types of ADO.NET data sets".

ADO.NET datasets are divided into typed datasets and untyped datasets, and a description of them is shown in the figure:

ADO.NET dataset type diagram

To access columns using typed datasets, see the following code:

String employeeName

EmployeeName = dsEmployees.Emp [0] .EmpName

Returns the EmpName column from the Emp table of the dsEmployees dataset and stores it in the employeeName string variable. To access columns using an untyped dataset, see the following code:

String employeeName; employeeName = dsEmployees.Tables ["Emp"] .Rows [0] ["EmpName"]

Use the Tables collection to return the EmpName column.

A little knowledge:

Typed DataSet and untyped DataSet

Typed DataSet, which is derived from DataSet, generates a dataset based on a pre-defined Data Schema and imposes strong type constraints on the fields in the dataset. You can see from the cs file it produces that many methods encapsulate the operation of DataTable so that you can access fields through MyDataSet.MyTable.Field instead of like DataSet:

MyDataSet.Tables ["TableName"] ["Field"]; simplifies programming without error-prone. Imagine that if you misspell the field name in "Field", the compiler won't check it, and you won't need typed DataSet. If you Field misspelled it, you'll know right away.

Also, if you include multiple datasets in Typed DataSet and establish relationships and constraints on those datasets in XSD, then Type DataSet will generate methods to reflect these relationships and constraints. If you use untyped DataSet, you need to do it yourself. Performance considerations: although Typed DataSet takes more time and space to create object instances than unTypede DataSet, it is faster to populate data than untyped DataSet, because DataAdapter already knows how to Fill a Typed DataSet. By contrast, DataSet needs to read the database twice, obtain the structure information of the tables in the database *, and fill the data the second time.

The drawback of Typed DataSet versus DataSet: Typed DataSet is not as flexible as DataSet in addition to the overhead of creation, because once Typed DataSet is determined, the structure of the data table is fixed and must be regenerated if it needs to be modified. On the other hand, you can do DataSet at any time as needed (such as adding fields, deleting fields, etc.).

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