Prince Sultan University
College of Computer & Information Sciences
Department of Computer Science
CS371: Web Development
Practice Sheet 6
TableModification and Updating Using a Grid
Using this worksheet you will learn how to modify and update database tables through a
grid control. The grid control is bound to the database table and provides command
columns to edit and update tables. To insert information in the table, the user is provided
with a set of textboxes to enter the required information. An Insert Button Click event is
programmed to insert a new row in the table (including the information entered by the
user)
The Data Tier:
Create the following stored procedures in your Database:
Insert a new category in your Categories table:
Note the use of parameters this time.
CREATE PROCEDURE InsertCategory
(@CategoryNameVARCHAR(50),
@CategoryDescriptionVARCHAR(50))
AS
INSERT INTO Categories (Name, Description)
VALUES (@CategoryName, @CategoryDescription)
RETURN
Update a category in your Categories table:
Again note the use of parameters
CREATE PROCEDURE UpdateCategory
(@CategoryIDINT,
@CategoryNameVARCHAR(50),
@CategoryDescriptionVARCHAR(1000))
AS
UPDATE Categories
SET Name = @CategoryName, Description = @CategoryDescription
WHERE ID = @CategoryID
RETURN
Delete a category from the table:
CREATE PROCEDURE DeleteCategory
(@CategoryIDINT)
AS
DELETE FROM Categories
WHERE ID = @CategoryID
RETURN
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Retrieve information from the table:
CREATE PROCEDURE GetCategory
AS
selectID, Name, Description from Categories
RETURN
The Presentation Tier:
Create the following controls on your form:
Note that last two columns in the grid are command columns that are added as follows:
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The Business Tier:
Add the following declarations at the beginning of the class:
int CGID;
stringCGName, CGDes; //Category name and description
// Instantiate the connection
SqlConnection conn;
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Create a Connection Object and Bind the grid to the table in the Page_Load()
method:
protectedvoidPage_Load(object sender, EventArgs e)
{
conn = newSqlConnection("Data Source=(local);Initial
Catalog=MyShop;Integrated Security=SSPI");
statusLabel.Text = conn.State.ToString();
// Load the grid only the first time the page is loaded
if (!Page.IsPostBack)
{
// Load the departments grid
BindGrid();
// Set control properties
statusLabel.ForeColor = System.Drawing.Color.Red;
}
}
Where BindGrid() is implemented as follows:
// Populate the GridView with data
privatevoidBindGrid()
{
// Get a DataTable object containing the catalog departments
Grid.DataSource = GetCategories();
// Bind the data bound controls to the data source
Grid.DataBind();
}
And the GetCategries Method is implemented as follows:
privateDataTableGetCategories()
{
SqlDataReaderrdr = null;
DataTable table;
try
{
// 1. Instantiate a new command with a query and connection
SqlCommandcmd = newSqlCommand("GetCategory", conn);
cmd.CommandType = CommandType.StoredProcedure;
// Open the connection
if (conn.State.ToString() == "Closed")
conn.Open();
// 2. Call Execute reader to get query results
rdr = cmd.ExecuteReader();
table = newDataTable();
table.Load(rdr);
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return table;
}
finally
{
// close the reader
if (rdr != null)
{
rdr.Close();
}
// Close the connection
if (conn != null)
{
conn.Close();
}
}
}
Implement the InsertCategory method as follows:
//Insert Data in Table
publicvoidInsertCategory(stringCatName, stringCatDescription)
{
try
{
// 1. Instantiate a new command with a query and connection
SqlCommandcmd = newSqlCommand("InsertCategory", conn);
cmd.CommandType = CommandType.StoredProcedure;
// 2. define parameters used in command object
SqlParameterparam = newSqlParameter();
param.ParameterName = "@CategoryName";
param.Value = CatName;
// 3. add new parameter to command object
cmd.Parameters.Add(param);
param = cmd.CreateParameter();
param.ParameterName = "@CategoryDescription";
param.Value = CatDescription;
// 3. add new parameter to command object
cmd.Parameters.Add(param);
// Open the connection
conn.Open();
// 2. Call ExecuteNonQuery to send command
cmd.ExecuteNonQuery();
BindGrid();
}
finally
{
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// Close the connection
if (conn != null)
{
conn.Close();
}
}
}
Implement the UPdateCategory Method as follows:
//Update Category Table
privateboolUpdateCategory(stringCatID, stringCatName, stringCatDescription)
{
try
{
// Open the connection
conn.Open();
// 1. Instantiate a new command with command text only
SqlCommandcmd = newSqlCommand("UpdateCategory");
cmd.CommandType = CommandType.StoredProcedure;
// 2. Set the Connection property
cmd.Connection = conn;
SqlParameterparam = newSqlParameter();
param.ParameterName = "@CategoryID";
param.Value = CatID;
// 3. add new parameter to command object
cmd.Parameters.Add(param);
param = cmd.CreateParameter();
param.ParameterName = "@CategoryName";
param.Value = CatName;
// 3. add new parameter to command object
cmd.Parameters.Add(param);
param = cmd.CreateParameter();
param.ParameterName = "@CategoryDescription";
param.Value = CatDescription;
// 3. add new parameter to command object
cmd.Parameters.Add(param);
// 3. Call ExecuteNonQuery to send command
int result;
result= cmd.ExecuteNonQuery();
BindGrid();
return (result != -1);
}
finally
{
// Close the connection
if (conn != null)
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{
conn.Close();
}
}
}
Implement the Delete Category Method as follows:
//Delete Data from table
publicboolDeleteCategory(stringCatID)
{
try
{
// Open the connection
conn.Open();
// 1. Instantiate a new command
SqlCommandcmd = newSqlCommand();
// 2. Set the CommandText property
cmd.CommandText = "DeleteCategory";
cmd.CommandType = CommandType.StoredProcedure;
// 3. Set the Connection property
cmd.Connection = conn;
SqlParameterparam = newSqlParameter();
param.ParameterName = "@CategoryID";
param.Value = CatID;
// 3. add new parameter to command object
cmd.Parameters.Add(param);
// 4. Call ExecuteNonQuery to send command
int result = -1;
result= cmd.ExecuteNonQuery();
BindGrid();
conn.Close();
return (result != -1);
}
finally
{
// Close the connection
if (conn != null)
{
conn.Close();
}
}
}
Back to the Presentation Tier:
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Implement the Insert Button Click event as follows:
protectedvoidbtnInsert_Click(object sender, EventArgs e)
{
CGName = txtName.Text; CGDes = txtDes.Text;
InsertCategory(CGName, CGDes);
BindGrid();
}
Implement the major Grid events as follows:
The RowEditing Event:
protectedvoidGrid_RowEditing(object sender, GridViewEditEventArgs e)
{
// Set the row for which to enable edit mode
Grid.EditIndex = e.NewEditIndex;
// Set status message
statusLabel.Text = "Editing row # " + e.NewEditIndex.ToString();
// Reload the grid
BindGrid();
}
The RowCancelingEdit Event:
protectedvoidGrid_RowCancelingEdit(object sender, GridViewCancelEditEventArgs e)
{
// Cancel edit mode
Grid.EditIndex = -1;
// Set status message
statusLabel.Text = "Editing canceled";
// Reload the grid
BindGrid();
}
The RowUpdating Event:
protectedvoidGrid_RowUpdating(object sender, GridViewUpdateEventArgs e)
{
// Retrieve updated data
string id = Grid.DataKeys[e.RowIndex].Value.ToString();
string name = ((TextBox)Grid.Rows[e.RowIndex].Cells[1].Controls[0]).Text;
string description =
((TextBox)Grid.Rows[e.RowIndex].Cells[2].Controls[0]).Text;
// Execute the update command
bool success = UpdateCategory(id, name, description);
// Cancel edit mode
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Grid.EditIndex = -1;
// Display status message
statusLabel.Text = success ?"Update successful" :"Update failed";
// Reload the grid
BindGrid();
}
The RowDeleting Event:
protectedvoidGrid_RowDeleting(object sender, GridViewDeleteEventArgs e)
{
// Get the ID of the record to be deleted
string id = Grid.DataKeys[e.RowIndex].Value.ToString();
// Execute the delete command
bool success = DeleteCategory(id);
// Cancel edit mode
Grid.EditIndex = -1;
// Display status message
statusLabel.Text = success ?"Delete successful" :"Delete failed";
// Reload the grid
BindGrid();
}
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