... visually create aDataReaderobjectinVisualStudio .NET (VS .NET) ; you can
only create them using program statements.
In this section, you'll see how to create a SqlDataReader object and use ... keyboard, or select Debug â Start
Without Debugging. Figure 9.4
shows the running form.
Figure 9.4: The running form
Using aDataReaderObjectinVisualStudio .NET
You can't visually ... from a SqlCommand object, which you saw how to create using VS .NET in the
previous chapter
. That SqlCommand object contained a SELECT statement that retrieved
the CustomerID, CompanyName, and...
...
Creating a Command ObjectUsingVisualStudio .NET
To create a SqlCommand objectusingVisualStudio .NET (VS .NET) , you drag a
SqlCommand object from the Data tab of the Toolbox ... named MyDataReader containing a Windows application.
2. Add a SqlConnection object to your project (refer back to the previous chapter
to
see how to add a SqlConnection objectusing VS .NET) . ... can also drag an
OleDbCommand object from the Data tab of the Toolbox to your form.
Before you perform the procedure explained in this section, do the following:
1. Create a new project named...
... Explorer-that's the best way to
learn.
Once you've connected to the database, you can view things such as the tables. You can
also retrieve and modify rows in the tables. You can drill ... by clicking the Show Diagram button in the
toolbar and selecting columns from the table, as shown in Figure 3.29
. As you can see,
I've selected the ContactName, CompanyName, and CustomerID ... the tables in the
database by clicking the Add icon in the tree in Server Explorer, and you can retrieve the
rows from a table by clicking the right mouse button on the table in the tree and...
... different
ways.
An interface cannot exist as an object: It has no code and no place to store object data. A
class that implements an interface has an explicit contract with the interface: The class ... Define a Class inVisual Basic .NET
Before writing code, you should take a moment to decide what data the class needs to
contain and what actions a developer (whether it is you or a teammate) ... CustomerID() As String
Parameterized Properties
You can also create properties that accept a parameter. For example, in the Northwind
database, a customer might have many orders. A parameterized...
... System.Reflection.Assembly.GetExecutingAssembly.Location
' Locate the last slash in the pathname string
Pos = InStrRev(AppPath, "/")
' Extract the part up to the backslash
AppPath = VB6.Left(AppPath, Pos)
' Initialise ... (Just -In-
Time) compiler rất hiệu năng ra machine code để chạy. Điểm này giúp
.NET application chạy nhanh hơn Java interpreted code trong Java
Virtual Machine. Just -In- Time cũng có ngh a là chỉ ... record và playback một chuổi công
tác.
Phương tiện Integrated Debugging cho ta Debug Menu, Call Stack
Window, Breakpoints Window và Watch and Value Display
Windows.
Thường thường bạn sẽ Add Reference...
... Dim AppPath As String
Dim Pos As Integer
' Fetch full pathname of the EXE file
AppPath = System.Reflection.Assembly.GetExecutingAssembly.Location
' Locate the last slash in the pathname ... MyBase.Load
' Obtain the folder where this program EXE resides and initialise tooltip
Các bài tập Microsoft .NET 34
' Obtain the Source ListItem String
LItem = e.Data.GetData(DataFormats.Text).ToString
... trình. Sau đó ta có thể viết:
AppPath = VB6.Left(AppPath, Pos)
Nguyên program chúng ta tại đây là Public Class Form1. Form1 th a kế
standard form class c a .NET Framework nên ta declare:
Inherits...
... loại cache database nho nhỏ (gọi là disconnected database) để
thay thế ADO. Thay vì application connects vĩnh viễn với database mẹ qua ADO,
application trong .NET làm việc với portable database ... từ database mẹ. Khi nào cần, portable database nầy (ADO .NET) sẽ được
reconciled với database mẹ để update các thay đổi. Hai tables trong ADO .NET có
thể được related nhau trong Master/Details ... relationship. Vì ADO .NET có
ch a original data lẫn data mới nhất nên Rollback trong ADO .NET rất dễ dàng
và nhẹ ký.
XML được yểm trợ tối a. Nằm ph a sau ADO .NET là XML. XML có thể là Table...
... trình. Sau đó ta có thể viết:
AppPath = VB6.Left(AppPath, Pos)
Nguyên program chúng ta tại đây là Public Class Form1. Form1 th a kế
standard form class c a .NET Framework nên ta declare: ... list of animals from a text file into Listbox2
Dim sr As StreamReader
Dim Pos As Integer
Dim TStr As String
ListBox2.Items.Clear() ' Clear Listbox2
' Use a StreamReader to ... sender As Object, ByVal e As
System.EventArgs) Handles Timer1.Tick
' Display Date and Time every half a second
Label3.Text = DateTime.Now.ToLongDateString & " " &
DateTime.Now.ToLongTimeString...
... using System;
using System.Data;
using System.Data.SqlClient;
class ConnectionPooling
{
public static void Main()
{
// create a SqlConnection object to connect to the database, ... ADO .NET automatically stores database connections ina pool. Connection
pooling offers a great performance improvement because you don't have to wait for a
brand new connection to the database ... SqlConnection object to connect to a SQL Server database
*/
using System;
using System.Data;
using System.Data.SqlClient;
class MySqlConnection
{
public static void Main()
{
// formulate a...
...
language
language
Compiler
Compiler
Bytecode
Bytecode
Results
JIT-compiler
JIT-compiler
Data
Data
Execution
Execution
.NET Framework & Visual Studio. NET
.NET Framework & Visual Studio. NET
NET Framework Base Class Library
NET Framework Base Class Library
Common Language Specification
Common Language Specification
ADO .NET: ... Forms
JScript
JScript
…
…
System.Drawing
System.Drawing
System.Windows.Forms
System.Windows.Forms
Windows
Windows
Forms
Forms
.NET Framework & Visual Studio. NET
.NET Framework & Visual Studio. NET
NET Framework Base Class Library
NET Framework Base Class Library
Common ... Class Library
NET Framework Base Class Library
Common Language Specification
Common Language Specification
Common Language Runtime
Common Language Runtime
ADO .NET: Data and XML
ADO .NET: Data and...