Rowupdating old values
Figure 4: Specify the Data to Retrieve Using an Ad-Hoc SQL Statement (Click to view full-size image) On the following screen, enter the SQL query to use to retrieve the product information. Discontinued = discontinued End Sub _ Public Function Update Product( By Val product Name As String, By Val supplier ID As Nullable(Of Integer), _ By Val category ID As Nullable(Of Integer), By Val quantity Per Unit As String, _ By Val unit Price As Nullable(Of Decimal), By Val units In Stock As Nullable(Of Short), _ By Val units On Order As Nullable(Of Short), By Val reorder Level As Nullable(Of Short), _ By Val discontinued As Boolean, By Val product ID As Integer, _ _ By Val original_product Name As String, _ By Val original_supplier ID As Nullable(Of Integer), _ By Val original_category ID As Nullable(Of Integer), _ By Val original_quantity Per Unit As String, _ By Val original_unit Price As Nullable(Of Decimal), _ By Val original_units In Stock As Nullable(Of Short), _ By Val original_units On Order As Nullable(Of Short), _ By Val original_reorder Level As Nullable(Of Short), _ By Val original_discontinued As Boolean, _ By Val original_product ID As Integer) _ As Boolean ' STEP 1: Read in the current database product information Dim products As _ Northwind Optimistic Concurrency.Let's use the exact same SQL query used for the SELECT Product ID, Product Name, Supplier ID, Category ID, Quantity Per Unit, Unit Price, Units In Stock, Units On Order, Reorder Level, Discontinued, (SELECT Category Name FROM Categories WHERE Categories. Category ID) as Category Name, (SELECT Company Name FROM Suppliers WHERE Suppliers. Supplier ID) as Supplier Name FROM Products Table Adapter in the Original DAL (Click to view full-size image) Before moving onto the next screen, click the Advanced Options button. Products Optimistic Concurrency Data Table = _ Adapter.aspdotnet-suresh offers C#articles and tutorials,csharp dot net,articles and tutorials, VB.For a web application that allows multiple users to edit data, there is the risk that two users may be editing the same data at the same time.The , that DB direct methods were those that accepts a list of scalar values as input parameters (rather than a strongly-typed Data Row or Data Table instance).When using optimistic concurrency, the DB direct method overloads that accept Data Rows and Data Tables rather than scalar values) must be changed as well.Jisun's changes to the product name have been overwritten.Figure 1 graphically depicts this series of events.
Optimistic concurrency control works by ensuring that the record being updated or deleted has the same values as it did when the updating or deleting process started.For example, imagine that two users, Jisun and Sam, were both visiting a page in our application that allowed visitors to update and delete the products through a Grid View control.