ASP.NET - insert - delete -update DataTables (disconnected datasets) Shopping Basket

Insert Using the INSERT SQL statement with data hard-wired into it Using the INSERT SQL statement with placeholder variables to be filled by user input. – Parameters.Add used to fill placeholders

Insert using SQL command Open connection to database as usual, then: Dim dothis As OleDbCommand Dim strInsert As String strInsert = "INSERT INTO Company (CompanyName, City) VALUES ('Blue Bird', 'Leeds')" dothis= New OleDbCommand(strInsert, objConn) dothis.ExecuteNonQuery

Insert using Add method of OleDbCommand Dim dothis As OleDbCommand Dim strInsert As String strInsert= "INSERT INTO Company (CompanyName, City) dothis= New OleDbCommand(strInsert, objConn) txtCompany.Text) txtCity.Text) Dothis.ExecuteNonQuery

Delete SQL DELETE command SQL DELETE with Parameters.Add

Delete using SQL Dim dothis As OleDbCommand Dim strDelete As String strDelete = “DELETE FROM” &;_ “Company WHERE CompanyName = ‘Blue Bird’” dothis= New OleDbCommand(strDelete, objConn) dothis.ExecuteNonQuery

Delete using Add method of OleDbCommand strDelete = “DELETE FROM Company WHERE CompanyName dothis= New OleDbCommand(strDelete, objConn) txtCompanyName.Text) dothis.ExecuteNonQuery

Update Executing an SQL statement with the UPDATE command against the database. SQL UPDATE with Parameters.Add

Update using SQL strUpdate = “UPDATE JobList SET EstimatedSalary = EstimatedSalary * 1.10 WHERE JobTitle = ‘Network Administrators’” dothis= New OleDbCommand(strUpdate, objConn) dothis.ExecuteNonQuery

Update using Add method of OleDbCommand strUpdate = “Update JobList SET EstimatedSalary WHERE JobTitle dothis= New OleDbCommand(strUpdate, objConn) txtEstimatedSalary.Text) txtJobTitle.Text) dothis.ExecuteNonQuery

DataTables Table stored in server memory Disconnected DataSet Used for – Manipulating subsets of data – Shopping basket

Defining a datatable 1 – define columns Dim objDT As System.Data.DataTable objDT = New System.Data.DataTable("Cart") objDT.Columns.Add("Product", GetType(String)) objDT.Columns.Add("Quantity", GetType(Integer)) objDT.Columns.Add("Cost", GetType(Decimal))

Data Table - Header Row Product Quantity Cost After step 1

Step 2 Adding a new row Dim objDR As System.Data.DataRow objDR = objDT.NewRow Part A – create a new blank row that copies the table

After Step 2a Data Table (objDT)- Header Row Product Quantity Cost DataRow (objDR)

2b – fill the new row objDR("Quantity") = txtQuantity.Text objDR("Product") = ddlProducts.SelectedItem.Text objDR("Cost") = Decimal.Parse(ddlProducts.SelectedItem.Value)

After step 2b Data Table (objDT)- Header Row Product Quantity Cost DataRow (objDR) Something some number some price

Step 3 – put the new row in the table objDT.Rows.Add(objDR)

After step 3 Data Table (objDT) Product Quantity Cost Something some number some price Header Row Row 1

Shopping Basket User not logged in* – Session – Datatable stored in memory User logged in – Session – Datatable to & from database * This version for coursework

Shopping Basket Initialise basket 1.Create a datatable 2.Store it in memory (Session) Session(“cart”)=objDT

Shopping basket (cont 2) When “add to cart” clicked 1.Retrieve the datatable from memory 2.Create a new row 3.Fill in the data 4.Put the new row on the bottom of the datatable basket = Session(“cart”)

Shopping basket (cont 3) View Basket 1.Retrieve table from memory 2.Bind table to DataGrid BasketGrid.DataSource()=Session(“cart”)

TO DO Oasisplus – ASP.NET : INSERT, DELETE, UPDATE – ASP.NET : DataList – Shopping basket example code on discussion board – Or start your coursework NEXT WEEK – SHOPPING BASKET Where we take items from a list retrieved from the database