Updating data sources with data adapters ado net house of blues dallas speed dating
After the data is retrieved and stored in a dataset, the connection with the database is closed. The dataset works as a virtual database containing tables, rows, and columns. Connection String = "Data Source=KABIR-DESKTOP; _ Initial Catalog=test DB; Integrated Security=True" connection. Tables(0) End Sub End Class We have discussed that the Data Set components like Data Table, Data Column and Data Row allow us to create tables, columns and rows, respectively.
The following diagram shows the dataset object model − The Data Set class is present in the System. The following table describes all the components of Data Set − Data Row It represents a row in the Data Table. Open() Dim adp As Sql Data Adapter = New Sql Data Adapter _ ("select * from Customers", connection) Dim ds As Data Set = New Data Set() adp. The following example demonstrates the concept − So far, we have used tables and databases already existing in our computer.
Retrieving Data Using a Data Reader Describes the ADO.
NET Data Reader object and how to use it to return a stream of results from a data source.
Populating a Data Set from a Data Adapter Describes how to fill a events and how to use them.
Applications communicate with a database, firstly, to retrieve the data stored there and present it in a user-friendly way, and secondly, to update the database by inserting, modifying and deleting data. An application accesses data either through a dataset or a data reader.
The objects to retrieve data from and resolve changes to the data source. NET Framework Data Provider for OLE DB includes an Ole Db Data Reader and an Ole Db Data Adapter object, the .
A Data Adapter is used to retrieve data from a data source and populate tables within a Data Set. NET Framework has a Db Data Reader and a Db Data Adapter object: the .
When you've finished, a further connection is made to the database to update it. for a fast-moving multi-user database you may want to keep it bang up to date; occasional saves within a long session will avoid everything being lost if there is an app or system crash; you might want to retrieve an autonumber ID of a new record to use in some other part of your app.
But, such cases apart, there is no need constantly to send data back to the database. Delete a record from a Data Table it is not immediately removed. Row State flag is set to Deleted so that, the next time the Data Adapter's .
We have a table stored in Microsoft SQL Server, named Customers, in a database named test DB. Sql Client Public Class Form1 Private Sub Form1_Load(sender As Object, e As Event Args) _ Handles My Base. String", "Student Name") Add New Column(Students, "System. Get Type(column Type)) End Sub 'adding data into the table Private Sub Add New Row(By Ref table As Data Table, By Ref id As Integer,_ By Ref name As String, By Ref city As String) Dim newrow As Data Row = table.
Please consult 'SQL Server' tutorial for creating databases and database tables in SQL Server. Take the following steps − When the application is run using Start button available at the Microsoft Visual Studio tool bar, it will show the following window − In this example, let us access data in a Data Grid View control using code. Load 'TODO: This line of code loads data into the 'Test DBData Set. String", "Student City") ' adding rows Add New Row(Students, 1, "Zara Ali", "Kolkata") Add New Row(Students, 2, "Shreya Sharma", "Delhi") Add New Row(Students, 3, "Rini Mukherjee", "Hyderabad") Add New Row(Students, 4, "Sunil Dubey", "Bikaner") Add New Row(Students, 5, "Rajat Mishra", "Patna") Return Students End Function Private Sub Add New Column(By Ref table As Data Table, _ By Val column Type As String, By Val column Name As String) Dim column As Data Column = _ table. New Row() newrow("Student ID") = id newrow("Student Name") = name newrow("Student City") = city table. Add(newrow) End Sub Private Sub Button1_Click(sender As Object, e As Event Args) Handles Button1.