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This article introduces the knowledge of "how to use DataTable objects in ADO". In the operation of actual cases, many people will encounter such a dilemma, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

The DataTable object is very similar to the Recordset object in ADO. The DataTable object allows you to view data through a collection of rows and columns, or you can store the query results in DataTable by calling the Fill method of the DataAdapter object, as shown in the following code:

Dim strConn, strSQL As String strConn = "Data Source=.\ SQLExpress;" & _ "Initial Catalog=Northwind;Integrated Security=True;" strSQL = "SELECT CustomerID, CompanyName FROM Customers" Dim da As New SqlDataAdapter (strSQL, strConn) Dim tbl As New DataTable () da.Fill (tbl) Visual C# string strConn, strSQL; strConn = @ "Data Source=.\ SQLExpress;" + "Initial Catalog=Northwind;Integrated Security=True;"; strSQL = "SELECT CustomerID, CompanyName FROM Customers"; SqlDataAdapter da = new SqlDataAdapter (strSQL, strConn); DataTable tbl = new DataTable () Da.Fill (tbl)

After the data is read from the database and stored in the DataTable object, the data is disconnected from the server. You can then view the contents of the DataTable object without generating any network traffic between the ADO.NET and the database. Because data is processed offline, there is no need to maintain an active connection to the database.

Keep in mind, however, that after running the query, you will not be able to see the changes made to the database by other users. The DataTable class contains a collection of other unconnected objects, which will be explained later. The contents of the DataTable can be accessed through its Rows property, which returns a collection of DataRow objects.

If you want to see the structure of DataTable, you can use its Columns property to get a collection of DataColumn objects. DataTable also allows you to define constraints, such as primary keys, for the data stored in this class. You can access these constraints through the Constraints property of the DataTable object.

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