Microsoft SQL Server 2005 Developer’s Guide- P49

Chia sẻ: Cong Thanh | Ngày: | Loại File: PDF | Số trang:10

Thêm vào BST

Báo xấu

46
lượt xem 2
download

Download Vui lòng tải xuống để xem tài liệu đầy đủ

Microsoft SQL Server 2005 Developer’s Guide- P49:SQL Server 2005 is a feature-rich release that provides a host of new tools and technologies for the database developer. This book is written to help database developers and DBAs become productive immediately with the new features and capabilities found in SQL Server 2005.

Chủ đề:

Bình luận(0) Đăng nhập để gửi bình luận!

Lưu

Nội dung Text: Microsoft SQL Server 2005 Developer’s Guide- P49

Chapter 12: Developing with SMO 459 TargetServerGroups Returns a Microsoft.SqlServer.Management.Smo .Agent.TargetServerGroupCollection that represents the target server groups deﬁned on SQL Server Agent. TargetServers Returns a Microsoft.SqlServer.Management.Smo.Agent .TargetServerCollection that represents the target server deﬁned on SQL Server Agent. NOTE This list represents only the major objects in the SMO JobServer object hierarchy. Many of these objects also contain their own objects, properties, and collections. Building the SMO Sample Application In the first part of this chapter, you had an overview of SMO objects, followed by an explanation of some of the most important SMO collections, methods, and properties. In the next part of the chapter, you learn how you can put SMO to work in a sample VB.NET program. Figure 12-3 presents the main screen of an example SMO application name SMOSample.exe that was built using VB.NET. Figure 12-3 A sample VB.NET SMO application
460 M i c r o s o f t S Q L S e r v e r 2 0 0 5 D e v e l o p e r ’s G u i d e This sample application demonstrates many of the essential techniques required to use SMO, including: Creating the Server object Connecting to a SQL Server system Using collections Getting speciﬁc objects from a collection Creating new database objects Copying existing database objects Disconnecting from a SQL Server system The sample application lists the registered SQL Server systems in a drop-down box, enabling the user to select the desired system to connect to. After selecting the desired SQL Server system, the user selects the appropriate authentication type. If SQL Server Authentication is selected, then the user is prompted to enter the Login ID and Password. If Windows Authentication is chosen, the user simply clicks the Connect button. Following a successful connection, the sample application lists all the databases the user is authorized to use. Lists showing the tables and columns for the first database in the list are filled in automatically. The Columns list is automatically filled in with the column names from the first table. Likewise, the Attributes list is filled in with the attributes of the first column in the list. Clicking any of the list items updates all the dependent lists. For instance, clicking a different database name causes the list of tables, columns, and column attributes to be updated with information from the newly selected database. And clicking a different item in the Tables list causes the Columns and Attributes lists to be updated with the column names and attributes of the selected table. Likewise, clicking a different entry in the column list updates the Attributes list with the attributes of the newly selected column. In addition to listing the SQL Server system’s databases schema, the sample SMO application also illustrates how SMO is capable of performing basic database management functions. Clicking Create Database prompts the user to create a new database. Clicking Copy Table lets the user create a copy of an existing table in the selected database. Likewise, clicking Show Keys displays the keys where a given column is used. Creating the Server Object The first thing the sample application needs to do is create an instance of the Server object. In the sample application, the Server object is shared by all the objects on the
Chapter 12: Developing with SMO 461 form, so it has been created using the following code in the Declarations section of the main Visual Basic form: Dim oSQLServer As New Server() Listing the Registered SQL Systems After a new global instance of the SMO object is instantiated in the project’s Declarations section, the list of registered SQL Server systems is retrieved during the initial Form_Load subroutine and displayed in a combo box enabling the user to select a specific SQL Server system. The code illustrating how to use SMO to retrieve the list of registered SQL Server systems is shown in the following listing: Private Sub Form_Load(ByVal sender As System.Object, _ ByVal e As System.EventArgs) Handles MyBase.Load Dim oRegisteredServers As RegisteredServers.RegisteredServer() = _ SmoApplication.SqlServerRegistrations.EnumRegisteredServers() ' Add each name to the combobox For Each oRegisteredServer As RegisteredServers.RegisteredServer _ In oRegisteredServers cboServer.Items.Add(oRegisteredServer.ServerInstance) Next End Sub In the beginning of the Form_Load subroutine, you can see where an instance of the RegisteredServer object is created and filled using the EnumRegisteredServers method of the SqlServerRegistrations class. Using this method is a vast improvement over SQL-DMO, as there is no longer any need to use a recursive loop through the servers and server groups to list the registered servers. Next, you see the For Each Loop read through all the individual SQL Server system names contained in the RegisteredServers collection. The registered systems objects are assigned to the oRegisteredServer object, and the Items.Add method of the cboServer combo box is used to add the value of the oRegisteredServer .ServerInstance property to the combo box’s drop-down list. Connecting to the Selected SQL Server System After an oSQLServer object is created, you can use the ServerConnection object’s connect method to establish a connection to a SQL Server system. In the sample application, the SQL Server connection is started after the user selects the name
462 M i c r o s o f t S Q L S e r v e r 2 0 0 5 D e v e l o p e r ’s G u i d e of the appropriate SQL Server system, then enters the appropriate authentication information, and then clicks Connect. Clicking Connect executes the following code in the cmdConnect_Click subroutine: Private Sub cmdConnect_Click(ByVal sender As System.Object, _ ByVal e As System.EventArgs) Handles cmdConnect.Click ResetScript() Dim oServerConn As New ServerConnection() oServerConn.ServerInstance = cboServer.Text oServerConn.LoginSecure = False Dim oDatabase As Database Try ' Setup a secure login for NT security If Me.optNTSecurity.Checked = True Then oServerConn.LoginSecure = True Else oServerConn.Login = txtLogin.Text oServerConn.Password = txtPwd.Text End If ' Connect to the selected SQL Server system oServerConn.Connect() oSQLServer = New Server(oServerConn) ' Disable the Connect button cmdConnect.Enabled = False ' List the databases For Each oDatabase In oSQLServer.Databases If oDatabase.Status DatabaseStatus.Inaccessible Then lstDatabases.Items.Add(oDatabase.Name) End If Next oDatabase ' Populate the other list boxes lstDatabases_Click(sender, e) ' Enable all of the other buttons cmdCreateDB.Enabled = True cmdTransferTables.Enabled = True cmdShowScript.Enabled = True Catch SQLSMOError() End Try End Sub
Chapter 12: Developing with SMO 463 In the beginning of this routine, an instance of Database is declared and named oDatabase. Next, the SMO ServerConnection object is declared and the server name from the cboServer drop-down box is put to the ServerInstance property. The ServerConnection object is also set with the LoginSecure type and Login and Password properties based on the security type selected by the user. Next, the oServerConn object is then passed as a parameter to the oSQLServer object’s constructor. If the user chose to use Windows Authentication, then the LoginSecure property of the oServerConn object is set to True, indicating that a trusted connection between SQL Server and NT will be used to authenticate the client. The Connect method could fail if the user enters an invalid SQL Server name or other invalid login information. As you can see in the cmdConnect_Click subroutine, a Try/Catch loop is used around the Connect method of the SMO objects. If the Connect method fails, a run-time error is generated and Visual Basic’s error handler is invoked. This causes control of the cmdConnect_Click subroutine to jump to the Catch portion of the Try/Catch loop, where the SQLSMOError function is executed. Handling SMO errors and the SQLSMOError subroutine is discussed later in this chapter. Listing Databases If the Connect method is successful, the cmdConnect_Click subroutine continues and the cmdConnect button is disabled, preventing the user from attempting to connect a second time. Next, the For Each loop is executed, which fills the list of databases on the SMO example program with the database names from the connected SQL Server system. The Databases property of the oSQLServer object contains a collection of the database names for the connected SQL Server. In the cmdConnect_Click subroutine shown previously, you can see how Visual Basic’s For Each operation is used to loop through the collection of database names and add each name to the list of databases. Each iteration of the For Each loop addresses a different Database object in the Databases collection. For instance, the first time the For Each loop is executed, the first Database object in the Databases collection is the current object. The second time the For Each loop is executed, the second Database object in the Databases collection is the current object. Within the For Each loop, first the database is tested to ensure that it’s accessible. For instance, the user running the application might not have permission to access the database. Next, the database name contained in the Name property of the current oDatabase object is added to the lstDatabases ListBox object using the Items.Add method. The For Each loop executes once for each object contained in the Databases collection.
464 M i c r o s o f t S Q L S e r v e r 2 0 0 5 D e v e l o p e r ’s G u i d e To fill out the Tables list, the Columns list, and the Columns attributes automatically, the cmdConnect_Click subroutine then executes the lstDatabases_Click subroutine, which retrieves a list of tables contained in the first database in the oDatabases collection. Listing Tables The code that retrieves the database table information for the sample application is executed either automatically at the end of the cmdConnect_Click subroutine or when the user clicks one of the database names in the list of databases. Both cases execute the lstDatabases_Click subroutine shown here: Private Sub lstDatabases_Click(ByVal sender As Object, _ ByVal e As System.EventArgs) Handles lstDatabases.Click ResetScript() Dim oCurDatabase As Database Dim oTable As Table Try ' Get the selected database name If lstDatabases.SelectedIndex >= 0 Then oCurDatabase = oSQLServer.Databases(lstDatabases.SelectedIndex) Else ' otherwise pick the first database oCurDatabase = oSQLServer.Databases(0) lstDatabases.SetSelected(0, True) End If ' Clear the dependant objects lstTables.Items.Clear() lstColumns.Items.Clear() txtAttributes.Text = vbNullString ' Add the table names to the list For Each oTable In oCurDatabase.Tables lstTables.Items.Add(oTable.Name) Next oTable ' Populate the dependant objects lstTables_Click(sender, e) Catch SQLSMOError() End Try End Sub At the top of the lstDatabases_Click subroutine, you can see where instances of the SMO Database object and the Table object are created. Next, the Try/Catch
Chapter 12: Developing with SMO 465 loop is set up to transfer control to the Catch tag and the SQLSMOError function to trap any run-time errors. Next, the SelectedIndex property of the lstDatabases list is checked to determine if this subroutine was evoked automatically by the cmdConnect_Click subroutine or by the user’s clicking one of the database names in the list of databases. If the value of the lstDatabases.SelectedIndex property is 0 or greater, then the user clicked one of the database list items and the program should display the tables for the selected database. Otherwise, if the lstDatabases .SelectedIndex property value is less than 0 (actually –1), then no user selection was made. The oCurDatabase object is set to the SelectedIndex property value of the Database objects contained in the oSQLServer.Databases collection. In other words, if the user clicks the fifth item in the lstDatabases ListBox, the lstDatabase .SelectedIndex property value will be used to set the oCurDatabase object to the fifth Database object in the oSQLServer.Databases collection. If no selection was made, the oCurDatabase object is set to the first Database object in the collection. Next, all the information currently displayed in the dependent interface objects is cleared. Then, Visual Basic’s For Each operation is used to list the members of the Tables collection. The For Each operation loops through the collection of SQL Server table names contained in the oCurDatabase object. Inside the For Each loop, the name of each member of the Tables collection is added to the lstTables list using the Items.Add method. Listing Columns After all the table names have been added to the list of tables, the lstTables_Click subroutine is executed to refresh the list of column names. The code that retrieves the names of the columns contained in a given table is executed either automatically at the end of the lstTables_Click subroutine or when the user clicks one of the table items displayed in the Tables list. In both instances, the lstTables_Click subroutine shown here is executed: Private Sub lstTables_Click(ByVal sender As Object, _ ByVal e As System.EventArgs) Handles lstTables.Click ResetScript() Dim oCurDatabase As Database Dim oCurTable As Table Dim oColumn As Column Try ' Get the selected table name If lstTables.SelectedIndex >= 0 Then oCurDatabase = oSQLServer.Databases(lstDatabases.SelectedIndex) oCurTable = oCurDatabase.Tables(lstTables.SelectedIndex) Else ' otherwise pick the first table
466 M i c r o s o f t S Q L S e r v e r 2 0 0 5 D e v e l o p e r ’s G u i d e oCurDatabase = oSQLServer.Databases(0) oCurTable = oCurDatabase.Tables(0) lstTables.SetSelected(0, True) End If ' Clear the dependant objects lstColumns.Items.Clear() txtAttributes.Text = vbNullString ' Add the column names to the list For Each oColumn In oCurTable.Columns lstColumns.Items.Add(oColumn.Name) Next oColumn ' Populate the dependant objects lstColumns_Click(sender, e) Catch SQLSMOError() End Try End Sub The lstTables_Click subroutine is structured much like the lstDatabases_Click subroutine. The first thing the lstTables_Click subroutine does is to make instances of the SMO Database, Table, and Column objects named oCurDatabase, oCurTable, and oColumn. Next, the lstTables_Click subroutine sets up the Try/Catch loop used to catch any errors generated and, subsequently, execute the SQLSMOError function. Then the lstTables.SelectedIndex property is tested to determine if this subroutine has been evoked automatically from the lstDatabases_Click subroutine or if this subroutine has been evoked by the user’s clicking one of the items in the lstTables list. If the lstTables_Click subroutine was called by the user’s clicking an entry in the lstTables list, then the oCurDatabase and oCurTable objects are assigned the value of the selected list items. Otherwise, the oCurDatabase and oCurTable variables are set to the first entry in each of their respective lists. After the variables containing the parent Database and Table names have been set, the old values in the lstColumns list and txtAttributes text box interface objects are cleared. This ensures that the lstColumns list and the txtAttributes text box will contain the values from the user’s new selection. Like the Databases and Tables collections, a For Each loop is used to iterate through the collection of Column objects. As the For Each loop progresses, the name of each current Column object is added to the lstColumns ListBox object. After all the names from the Columns collection have been added to the lstColumns list, the lstColumns_Click subroutine is called to retrieve a subset of the specific attributes of a selected column.
Chapter 12: Developing with SMO 467 Retrieving Column Attributes The code that retrieves the attributes of a specific column is executed either automatically at the end of the lstColumn_Click subroutine or when the user clicks an item in the Columns list. The lstColumns_Click subroutine shown here is executed for both of these actions: Private Sub lstColumns_Click(ByVal sender As Object, _ ByVal e As System.EventArgs) Handles lstColumns.Click ResetScript() Dim oCurDatabase As Database Dim oCurTable As Table Dim oColumn As Column Try ' Get the selected column name If lstColumns.SelectedIndex >= 0 Then oCurDatabase = oSQLServer.Databases(lstDatabases.SelectedIndex) oCurTable = oCurDatabase.Tables(lstTables.SelectedIndex) oColumn = oCurTable.Columns(lstColumns.SelectedIndex) Else ' otherwise pick the first column oCurDatabase = oSQLServer.Databases(0) oCurTable = oCurDatabase.Tables(0) oColumn = oCurTable.Columns(0) lstColumns.SetSelected(0, True) End If ' Clear the dependant objects txtAttributes.Text = vbNullString ' Add the attributes to the textbox txtAttributes.Text = oColumn.Name.ToString() _ & vbCrLf & vbCrLf _ & "Data Type:" & vbCrLf _ & oColumn.DataType.ToString() & vbCrLf & vbCrLf _ & "Length:" & vbCrLf _ & oColumn.Properties.Item("Length").Value.ToString() _ & vbCrLf & vbCrLf _ & "Precision:" & vbCrLf _ & oColumn.Properties.Item("NumericPrecision").Value.ToString() _ & vbCrLf & vbCrLf _ & "Scale:" & vbCrLf _ & oColumn.Properties.Item("NumericScale").Value.ToString() Catch ex As Exception SQLSMOError() End Try End Sub
468 M i c r o s o f t S Q L S e r v e r 2 0 0 5 D e v e l o p e r ’s G u i d e Again, the lstColumns_Click subroutine starts by declaring instances of the SMO Database, Table, and Column objects. Like the other subroutines, the lstColumns_Click subroutine then determines if the user has clicked an entry in the lstColumns list or if the lstColumns_Click subroutine was called automatically from the lstTables_Click subroutine. If the user has clicked one of the lstColumn items, then the oCurDatabase, oCurTable, and oColumn variables are assigned the select list items. Otherwise, the oCurDatabase, oCurTable, and oColumn variables are assigned the first item in each of the respective lists. Next, the txtAttributes.Text property is cleared. You might notice that unlike the other subroutines, the lstTables_Click subroutine doesn’t use a list box or iterate through a collection. Instead, the lstColumns_Click subroutine displays a selection of properties from one specific member of the Columns collection. The following properties of the Column object are displayed: Name DataType Length NumericPrecision NumericScale The txtAttributes text box has the Multiline property enabled, which allows multiple lines to be displayed in the text box. Each line is separated by CR + LF characters, which are represented by the vbCrLf constant. Creating Databases The earlier examples in this chapter illustrated how to list the various SQL Server database objects using SMO collections. SMO is capable of far more than listing databases or tables, however. SMO’s extensive object framework lets you perform virtually any management function that can be performed using the SQL Server Enterprise Manager. The following example illustrates how SMO can be used to create a new SQL Server database programmatically. The cmdCreateDB_Click subroutine is executed when the user clicks the Create Database button provided by the SMOSample application, shown earlier in Figure 12-3. The code for the cmdCreateDB_Click subroutine is shown in the following listing: