Friday, April 21, 2017

SSIS Tricks: Control executing the next SSIS tasks

Your SSIS package may requrie to have control that will make decision if the next SSIS tasks will execute or not. I have an example where 'Data Flow Task' for loading the fact table will start if 'Execute SQL  Task' return TRUE.

Here as an example; I have a sequence container that look like below:
Fig 1: Execute SQL task and  Data flow task

Let's look at the code in SQL Execute task named "Control Fact Load":

Fig 2: SQL query for SQL Execute Task

The SQL code in the above diagram:

SELECT case when max([TimeKey])<convert(varchar(8),getdate(),112)
                      Then 'Y' 
                    Else 'N'
         END  as GoToNextStep
                FROM [dbo].[Fact_XXX]

The SQL code in the above diagram intend to find if there is any Date exist in the fact table bigger than today. It means if the fact table's date "TimeKey" is less than today's date then we retutn 'Y' ; so, we did not load any data for today yet. And if today's date is already exist it means data is uploaded to the fact already then we return 'N' hence next SSIS task will not execute.

The return value of the SQL need to save in a variable. So user variable GoToNextStep is created and assigned the value after the Execute SQL task as like below:
Fig 4: User variable created
And then assigned the value after SQL execute task:

Fig 5: Binding value to the variable

The way we control between two tasks is precedence constraint.

Fig 6: Prcedence constraint editior

You need to open the prcedence constraint editior (right click the connector between two tasks) and then set the value as like below:
Evaluation operation: Expression and Constraint
Expression: @[User::GoToNextStep]=="Y"

Now, Data Flow Task (Load Data To Target table) will only execute if prior Exceute SQL task (Control Fact Load) return "Y". If 'N' is returned via Exceute SQL task (Control Fact Load) then next data flow task (Load Data To Target table) will not execute at all.

Sunday, April 2, 2017

How to atuomate SFTP file transfer in Windows

When it comes to loading file to the FTP server then we use different free FTP/SFTP client like WinSCP, FileZilla etc. The process of uploading files is completely manual in this way. If your business needs to upload files repeatedly then the process should be automated.

My writing will cover how this can be done in Microsoft windows.
For example you have a file called UploadMe.txt which is located in C:\temp. Now we would like to upload this file to the SFTP Server. Before we start using  script, let's see how we do in WinSCP.

Fig 1: WinSCP  User Interface

As we can see, we need following information to connect the FTP/SFTP server, I have put the information as an example:

Host name:
Port number: 22
User bane: myuser
Password: Password

And when you are connected to the SFTP server then you drag files from your local machine and drop the files to the server.
Fig 2: Moving file from local PC to SFTP Server

How do we do the same thing by using script?

Step 1: You need to install WinSCP, so go to the : and download it.
Fig 3: Download WinSCP 

Step 2: Script for establishment of connection to the SFTP server and move the file from your machine to the Server. So the script should cover at least below:

a) Opening a connection the SFTP server, below syntax will open the connection:
open s

b) Syntax for copying data from local machine to FTP server:
put -nopermissions -nopreservetime "C:\temp\test_data.txt"  test_script.txt

Lets make full script in one place and save the file as 'uploadscript.txt'

option echo off
option batch on
option confirm off
open s
#Change LOCAL directory
lcd "C:\temp\"
#copy an individual file
put -nopermissions -nopreservetime "C:\temp\test_data.txt"  test_data.txt

Before we run the above script through .bat file, we would like to test if we can connect with FTP server and load the file by using command windows.

Fig 4: windows Command line
Change the path to WinSCP so that we can use WinSCP resources:

Fig 5: Accessing WinSCP file

Run the script which will make connection with the SFTP Server and copy the file to the server.

Fig 6: Make connection and move file

As you can see from the above screenshot (fig 6), SFTP server connection is made and started loading the file.

However, above process is done through windows command line to see if we can establish connection and transfer file. Since we would like to make it automated so we need to make a batch file and run the script ('uploadscript.txt') that we just run through windows Command line. And last step is to schedule the task via windows Task Schedular, hurrah, now your file will be automatically upload to the SFTP server as schedule them.