Tài liệu Create a Detach/Attach SQL Server Database Dialog Box ppt

You can select a database, such as the one displayed in Figure 7.11, and click the Detach button.. You can then type in the name you want to attach the database as, and click on the Loca

7.5 Create a Detach/Attach SQL Server Database Dialog Box

Situations sometimes arise that require a database to be attached, detached, or both

Perhaps your client needs to move the database from one SQL Server to another This How-To shows you the methods you can use to perform these tasks

Before diving into solving some of the tasks that can be accomplished in the How-Tos just listed, it's important to discuss the SQL-DMO object model, as well as create a

reference to it

Many times, you've used the Enterprise Manager to move databases for users by

attaching and detaching them It would be nice to be able to perform this task without users calling you At he very least, you'd like to be able to walk users through the details over the phone, without having to use the Enterprise Manager How do you create a dialog box to perform this task?

Technique

This is probably the easiest of the How-Tos to create for this chapter, other than How-To 7.1 For this task, you will be using two methods of the SQLServer object: DetachDB and AttachDBWithSingleFile

Along with the two methods just mentioned, you will also be using a Tab control to choose which task to perform, as well as an OpenFile Dialog control to allow the user to choose the file to attach

Steps

Open and run the VB.NET -Chapter 7 solution From the main Windows form, click on the command button with the caption How-To 7.5 You can select a database, such as the one displayed in Figure 7.11, and click the Detach button You will see the database disappear from the list of databases to choose from

Figure 7.11 Ready to detach the chosen database

After you have chosen the database, you can reattach the database by clicking on the tab labeled Attach Database You can then type in the name you want to attach the database

as, and click on the Locate File button to locate the database file to attach (see Figure 7.12.)

Figure 7.12 Choosing the database file to attach

Select the file and click Open To attach the file, click the Attach Database button The database file will then be attached, and you can see it in the list of databases To check this, you can look at the list back on the Detach Database tab; that list was refreshed when you clicked the Attach Database button

1 Create a Windows Form

2 Add a Tab control from the Windows Form Controls list Click the builder button

in the Tab Pages property, and add two pages Set the Text property for Page1 to Detach Database, and the Text property for Page2 to Attach Database

3 Add an OpenFileDialog control from the Windows Form Controls list Go ahead and leave the default name given to the control, but make a note of it

4 Place the other controls shown in Figure 7.10 and 7.11, with the following

properties set as in Table 7.9

Table 7.9 Label, ListBox, and Command Button Controls Property Settings

ListBox Main Form Name lstSQLServers

ListBox Tab Page1 Name lstDatabases

TextBox Tab Page2 Name txtFileToAttach

TextBox Tab Page2 Name txtNameOfAttach

5 On the form, add the code in Listing 7.24 to the Load event This will look familiar from How-To 7.1 For an examination of the LoadSQLServers routine, check out step 4 in that How-To

Listing 7.24 frmHowTo7_5.vb: Calling the Routine That Loads Available SQL Servers into a List Box

Private Sub frmHowTo7_5_Load(ByVal sender As System.Object, _

ByVal e As System.EventArgs) Handles MyBase.Load

LoadSQLServers(Me.lstSQLServers)

End Sub

6 On the lstSQLServers list box, add the code in Listing 7.25 to the

SelectedIndexChanged event This routine toggles the btnDetach button,

depending on whether a SQL Server and database has been selected It then calls GetSQLDatabases, described in step 6 of How-To 7.1

Listing 7.25 frmHowTo7_5.vb: Populating the lstDatabases List Boxes

Private Sub lstSQLServers_SelectedIndexChanged(ByVal sender As

System.Object,

ByVal e As System.EventArgs) _

Handles lstSQLServers.SelectedIndexChanged

If lstSQLServers.SelectedItems.Count > 0 And _

lstDatabases.SelectedItems.Count > 0 Then

Me.btnDetach.Enabled = True

Else

Me.btnDetach.Enabled = False

End If

GetSQLDatabases(Me.lstSQLServers.SelectedItem, Me.lstDatabases) End Sub

7 On the lstDatabases list box, add the code in Listing 7.26 to the

SelectedIndexChanged event This routine toggles the btnDetach button,

depending on whether a SQL Server and database have been selected

Listing 7.26 frmHowTo7_5.vb: Toggling the btnDetach Button Based on Whether a SQL Server and Database Have Been Chosen

Private Sub lstDatabases_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) _

Handles lstDatabases.SelectedIndexChanged

If lstSQLServers.SelectedItems.Count > 0 And _

lstDatabases.SelectedItems.Count > 0 Then

Me.btnDetach.Enabled = True

Else

Me.btnDetach.Enabled = False

End If

End Sub

8 On the btnDetach button, add the code in Listing 7.27 to the Click event After connecting to the server, the DetachDB method is called Then the

GetSQLDatabases routine is called to refresh the database list

Listing 7.27 frmHowTo7_5.vb: Detaching a SQL Server Database

Private Sub btnDetach_Click(ByVal sender As System.Object, _

ByVal e As System.EventArgs) Handles btnDetach.Click

Dim oSQLSvr As New SQLDMO.SQLServer()

Dim strDetachMsg As String

Try

' Connect to the server

oSQLSvr.LoginSecure = True

oSQLSvr.Connect(Me.lstSQLServers.SelectedItem)

' Perform the detach

strDetachMsg = oSQLSvr.DetachDB(Me.lstDatabases.SelectedItem)

' Refresh the databases

GetSQLDatabases(Me.lstSQLServers.SelectedItem, Me.lstDatabases)

Catch excp As Exception

MessageBox.Show(excp.Message)

Exit Sub

End Try

MessageBox.Show("Database Detached")

End Sub

9 Add the code in Listing 7.28 to the Click event of btnLocateFile This routine uses the OpenFileDialog control to retrieve the name of the file you want to attach

Listing 7.28 frmHowTo7_5.vb: Locating the Database File to Attach

Private Sub btnLocateFile_Click(ByVal sender As System.Object, _

ByVal e As System.EventArgs) Handles btnLocateFile.Click

With OpenFileDialog1

InitialDirectory = _

"E:\Program Files\Microsoft SQL Server\MSSQL\Data\"

Filter = "SQL Server Database files (*.mdf)|*.mdf"

ShowDialog()

Me.txtFileToAttach.Text = FileName

End With

End Sub

10 Add the code in Listing 7.29 to the TextChanged event of txtFileToAttach and txtNameToAttach as appropriate

Listing 7.29 frmHowTo7_5.vb: Closing the Form

Private Sub txtFileToAttach_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles txtFileToAttach.TextChanged

If Len(Me.txtFileToAttach.Text) > 0 And _

Len(Me.txtNameOfAttach.Text) > 0 Then

Me.btnAttach.Enabled = True

Else

Me.btnAttach.Enabled = False

End If

End Sub

Private Sub txtNameOfAttach_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles txtNameOfAttach.TextChanged

If Len(Me.txtFileToAttach.Text) > 0 And _

Len(Me.txtNameOfAttach.Text) > 0 Then

Me.btnAttach.Enabled = True

Else

Me.btnAttach.Enabled = False

End If

End Sub

11 Add the code in Listing 7.30 to the Click event of btnAttach After connecting to the server, this code calls the AttachDBWithSingleFile method Then it refreshes the database list using the routine GetSQLDatabases

Listing 7.30 frmHowTo7_5.vb: Attaching a SQL Server Database

Private Sub btnAttach_Click(ByVal sender As System.Object, _

ByVal e As System.EventArgs) Handles btnAttach.Click

Dim oSQLSvr As New SQLDMO.SQLServer()

Dim strAttachMsg As String

Try

oSQLSvr.LoginSecure = True

oSQLSvr.Connect(Me.lstSQLServers.SelectedItem)

' Attach the database

strAttachMsg = oSQLSvr.AttachDBWithSingleFile( _

Me.txtNameOfAttach.Text, Me.txtFileToAttach.Text)

' Refresh the databases

GetSQLDatabases(Me.lstSQLServers.SelectedItem, Me.lstDatabases)

Catch excp As Exception

MessageBox.Show(excp.Message)

Exit Sub

End Try

MessageBox.Show("Database Attached")

End Sub

How It Works

This How-To uses the DetachDB and AttachDBWithSingleFile methods to attach and detach a database

Comments

You can enhance this routine by allowing for databases that have multiple files to be attached and detached

There is so much you can do with the APIs that SQL Server provides Open the

Enterprise Manager and look at some of the various utilities, including Data

Transformation Services Then open the Object Browser to the SQL-DMO and SQL-DTS libraries, and notice the correlation between tasks that are displayed using the Enterprise Manager and the APIs