A primary key in a relational database is a column or combination of columns that always contain unique values. Write Line("Rows after merge.") Dim row As Data Row For Each row In shipper. Write Line(": ", row(0), row(1)) Next End Using End Sub event handler checks the Statement Type of the Sql Row Updated Event Args to determine if the row is an insert. Skip Current Row End If End Sub values from a Jet 4.0 database. Text ' Add the parameter for the Category Name.

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The When working with Microsoft SQL Server, you can create a stored procedure with an output parameter to return the identity value for an inserted row. Shippers " & _ "WHERE Shipper ID = SCOPE_IDENTITY();", _ connection) ' Add the parameter for the inserted value.

The following table describes the three Transact-SQL functions in SQL Server that can be used to retrieve identity column values.

Relational database engines, such as SQL Server, Oracle, and Microsoft Access/Jet support the creation of automatically incrementing columns that can be designated as primary keys. The row is updated, but the original values in the row are preserved. Dim adapter As Ole Db Data Adapter = New Ole Db Data Adapter( _ "SELECT Category ID, Category Name FROM Categories", _ connection) ' Create the INSERT command for the new category. Insert Command = New Ole Db Command( _ "INSERT INTO Categories (Category Name) Values(?

These values are generated by the server as rows are added to a table. Write Line("List All Rows:") Dim row As Data Row For Each row In categories. Write Line(": ", row(0), row(1)) Next End Using End Sub . Row Updated, New _ Sql Row Updated Event Handler(Address Of On Row Updated) ' Update the datasource with the modified records. Update(data Changes) ' Merge the two Data Tables. In the main body of the procedure, the Merge method is called to merge the new identity value into the original Private Sub On Row Updated( _ By Val sender As Object, By Val e As Sql Row Updated Event Args) ' If this is an insert, then skip this row.

However, you might end up with duplicate values in separate instances of a Data Table, if multiple client applications are independently generating automatically incrementing values. New Row() new Row("Category Name") = "New Category" categories. How the command results are applied to each Data Row being updated is determined by the Updated Row Source property of each Db Command.

Having the server generate automatically incrementing values eliminates potential conflicts by allowing each user to retrieve the generated value for each inserted row. Dim categories As Data Table = New Data Table adapter. This property is set to a value from the and using a Sql Data Adapter to update the data source and retrieve a new identity column value.

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