Create a Detach/Attach SQL Server Database Dialog Box

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7,5 Tạo một Tháo / Đính kèm SQL Server cơ sở dữ liệu Dialog Box trạng đôi khi phát sinh đòi hỏi một cơ sở dữ liệu được đính kèm, tách ra, hoặc cả hai.

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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 Object Location Property Setting Label Main Form Name Label1 Text SQL Servers ListBox Main Form Name lstSQLServers Label Main Form Name Label2 Text Databases ListBox Tab Page1 Name lstDatabases Button Tab Page1 Name btnDetach Text &Detach Database Label Tab Page2 Name Label3 Text File to Attach TextBox Tab Page2 Name txtFileToAttach Label Tab Page2 Name Label4 Text Name of Attached Database TextBox Tab Page2 Name txtNameOfAttach Button Tab Page2 Name btnLocate Text &Locate File Button Tab Page2 Name btnAttach Text &Attach Database
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.