I would suggest that you read the part 1 of this article before going through this one. The major details of the SQLDMO are discussed in the part 1 of this article. We have upgraded the component to be used with SQL server 7.0. The code in the previous article worked only with the version 6.5 of the SQL Server. More enhancements are made in the new component, the new component is capable of deleting the task automatically once the task has been accomplished. In the previous version, the task once created has to be removed manually by executing a method called as “RemoveTask” but there is no need for such method in the new component as it will delete the task upon successful completion. Furthermore, earlier the task was executed each time a specific date was reached but now the task will execute only once at a specific date the user will supply to the component. Also, we have demonstrated how to add two steps in the same job. In the previous article the job consisted of only one step but the new tasks created with the new component shall consist of more than one job step, that is, user can accomplish more than one job within the same task. Now, lets go through the code step by step:
Private Sub Class_Initialize() On Error Resume Next NL = Chr$(13) & Chr$(10) Set oSQLServer = New SQLDMO.SQLServer oSQLServer.LoginTimeout = 10 End Sub
The main object is created when the class is initialized, similarly this object shall be deleted from the memory when the class is terminated.
Our main method is known as AddTask, this method will add a new task to the task scheduler, note we have not passed the parameters directly to function instead we have used the properties to get the input from the user.
Public Function AddTask() On Error GoTo errhandler oSQLServer.DisConnect Disconnect the server if its already connected. If Server = "" Then ErrDesc = "You must enter server name." Exit Function ElseIf UserID = "" Then ErrDesc = "You must enter a valid User ID" Exit Function ElseIf Password = "" Then Password = "" End If
Get values of important parameters from the user, these values are needed to connect to the sqlserver.
'Connect to the server! oSQLServer.Connect CStr(Server), CStr(UserID), CStr(Password) Dim oJob As New SQLDMO.Job Dim idStep As Integer
Idstep will be used to define the total number of steps to be included in the task.
'Set the schedule name oJob.Name = JobID
Assign a name to the job.
'objSQLServer.Executive.Tasks.Add oJob oSQLServer.JobServer.Jobs.Add oJob
Add the newly created job to the job server. The jobserver object exposes attributes associated with SQL server agent. SQL Server agent is responsible for executing the scheduled jobs and notifying operators of SQL Server error conditions or other SQL Server execution or job states.
'Use the code below to change the task!!! oJob.BeginAlter 'idStep = 0
Initially we have assigned a zero value to the step id. Because we intend to add two steps in our task, so we run a loop twice.
For idStep = 0 To 2 Dim oJobStep As SQLDMO.JobStep Set oJobStep = New SQLDMO.JobStep
We have created a new job step object in the statements above. The jobstep object exposes the attributes of a single SQL Server agent executable job step. SQL Server Agent jobs contain one or more execution units called steps. Each job step contains a textual command, type of execution that specifies command interpretation, and logic that determines the behaviour of the job if the step succeeds or fails
idStep = idStep + 1 oJobStep.Name = JobID & idStep oJobStep.StepID = idStep 'Set the job step executable subsystem. oJobStep.SubSystem = "TSQL"
The subsystem property specifies the SQL Server Agent execution subsystem used to interpret job step task-defining text.
If DatabaseName <> "" Then oJobStep.DatabaseName = DatabaseName Else oJobStep.DatabaseName = "yourdatabase" End If
If the user fails to pass the database name from the front end than the component will pick up the hardcoded database name provided that you have hardcoded the database name in your code.
If idStep = "1" Then If CommandText <> "" Then oJobStep.Command = CommandText Else oJobStep.Command = "select * from table1" oJobStep.OnSuccessAction = SQLDMOJobStepAction_GotoNextStep End If Else oJobStep.StepID = 2 If Commandtext2 <> "" Then oJobStep.Command = Commandtext2 Else oJobStep.Command = "delete from table2" oJobStep.OnSuccessAction = SQLDMOJobStepAction_QuitWithSuccess End If End If
We have added two commands to the jobs, one will return all the records from the table and the second will delete all the records from the particular table, this has been done just to give you an example, you can do whatever you want with your database tables by passing the command text either from the front end or by hardcoding the command text in the code as seen above.
oJob.JobSteps.Add oJobStep Next
Add the individual job step to the jobsteps collection.
'Set the Target Server oJob.ApplyToTargetServer (CStr(Server))
The applytotargetserver method adds an execution target to the list of targets maintained for the referenced SQL Server Agent job.
Now, here comes the important part, the scheduling of the job, the job has been created but now we have to schedule the job so that it runs at a specific date and time.
JobSchedule object exposes the attributes of a single SQL Server Agent executable job schedule.
Dim oJobSchedule As SQLDMO.JobSchedule Set oJobSchedule = New SQLDMO.JobSchedule 'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx 'Schedule the task! 'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
You can calculate any time and date for your task to start execution, it solely depends on your choice or requirement. We have calculated the year, month and day separately.
Dim startyear, startmonth, startday 'Indicate execution scheduled for everyday by using 'the FrequencyType and FrequencyInterval properties. oJobSchedule.Name = JobID oJobSchedule.Schedule.FrequencyType = SQLDMOFreq_OneTime
We want to execute the task only once so we have set the frequency type to single time.
'Set the ActiveStartDate to indicating the date on 'which the schedule becomes active. Start date is 'today's date Dim mydate mydate = DateAdd("h", CInt(Num_Of_Hours), Now()) Dim hr, min, sec hr = Hour(mydate) min = Minute(mydate) sec = Second(mydate) Dim mytime mytime = hr & min & sec startyear = DatePart("yyyy", mydate) startmonth = DatePart("m", mydate) startday = DatePart("d", mydate) If Len(startmonth) < 2 Then startmonth = "0" & startmonth If Len(startday) < 2 Then startday = "0" & startday oJobSchedule.Schedule.ActiveStartDate = startyear & startmonth & startday
Activestartdate property indicates the first effective date for a schedule.
'Set the ActiveStartTimeOfDay property to indicate the 'scheduled execution time on each day oJobSchedule.Schedule.ActiveStartTimeOfDay = mytime
Activestarttimeofday property indicates the start time of the day for a schedule.
'Indicate that the schedule never expires oJobSchedule.Schedule.ActiveEndDate = SQLDMO_NOENDDATE oJobSchedule.Schedule.ActiveEndTimeOfDay = SQLDMO_NOENDTIME
Similarly, we have to provide the activeenddate and time for the job. We have set these properties to “SQLDMO_NOENDDATE” and “SQLDMO_NOENDTIME” which means that the job will never expire until is executed.
'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx 'Add task to scheduler 'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx oJob.JobSchedules.Add oJobSchedule
Now here is the clever part, that is, how to remove the task from the scheduler automatically, there is a property named as deletelevel which controls post-execution processing for SQL Server Agent jobs.
'Automatically delete job after successful completion oJob.DeleteLevel = SQLDMOComp_Success
If the job is successful then we delete the job from the scheduler.
oJobStep.OnFailAction = SQLDMOJobStepAction_QuitWithFailure If SQLDMOJobStepAction_QuitWithFailure = True Then ErrDesc = "Failure" Else ErrDesc = "Success" End If oJob.StartStepID = 1 'Alter the job oJob.DoAlter 'Clear references to the created objects Set oJob = Nothing Set oJobStep = Nothing Set oJobSchedule = Nothing Exit Function errhandler: 'Clear references to the created objects Set oJob = Nothing Set oJobStep = Nothing Set oJobSchedule = Nothing ErrDesc = "Failure: " & "'" & Err.Source & "'" & " " & Err.Number & " " & Err.Description End Function
Rest of the code is similar to the one we saw in the first part, destroy the object when the class terminates. Compile the DLL and access the component either in your VB project or ASP code. It works fine and efficiently. You can customize the component to add more features or to change the functionality according to your own needs.
There is a difference in SQLOLE and SQLDMO, SQLOLE.DLL library comes with SQL Server 6.5 while SQLDMO.DLL library comes with SQL Server 7.0. You will have to include the correct reference to the library, In case of this article, add the reference to the SQLDMO.DLL reference.
S.S. Ahmed is a senior software engineer and works for a web and software development firm. Ahmed specializes in creating database driven dynamic web sites. He uses ASP and VB for most of what he develops. Ahmed likes to hop into other tools as well. Ahmed has worked in Assembly language, C, C++, FoxPro, QBasic, All version of Visual Basic (currently experimenting with VB.NET), Visual C, Java, ASP, etc. Ahmed enjoys travelling and has been to many parts of the world. Ahmed can be reached at [email protected]
本文地址：http://com.8s8s.com/it/it6438.htm