SSIS Lesson 3 – Derived Column

In this lesson, we are going to take the first basic step towards building a data warehouse. We are going to create a historical table from the table we built in Lesson 2. If you didn’t do Lesson 2, you can find the SQL needed to build the table at the bottom of this lesson.

If you remember the table we built in Lesson 2, we had a list of students and the work teams they were assigned to. In lesson 2, this list was designed to change every week, and we only wanted to know what the current week data was.  However, now Principal Skinner has asked if we can keep a listing of all the weeks so he can go back and see how many times someone was assigned to one of the work teams.

The table below is our starting table.

What we want to do is copy the table’s contents into a new historical table and mark it somehow so we know what week each kid was on each team. We are going to do this by creating a new column called INSERT_DT which will record the date the data was added to the historical table.

First things first, let’s build our historical table in SQL Server

CREATE TABLE [dbo].[STUDENT_TEAM_HIST](
       [STUDENT_NM] [varchar](50) NULL,
       [STUDENT_AGE] [int] NULL,
       [STUDENT_TEAM] [varchar](50) NULL,
       [INSERT_DT] [datetime] NULL
)

Now go into SSIS and go to your Training Project

Create a new Package, I called mine Lesson_3

Drag a Data Flow object onto your design window and click on it

Now drag an OLE DB Source box over and click on it

Select dbo.Student_Name from the drop down and click OK

Now we are going to use a new object – Derived Column, drag it over and connect the Blue arrow from the bottom of the OLE DB Source box to it

Click on Derived Column: Purple Arrow (far left) – Name your new column, I named mine INSERT_DT

Green Arrow (Middle) : in the Expression column, type GETDATE()

Yellow Arrow (far right) : once you tab out of the Expression column, you will see your Data Type changed itself to be a timestamp

Red Arrow (Bottom) : hit Okay

What we just did was create a new column called INSERT_DT which will use the GETDATE() method to get the current date and time. Next we are going to use this column we just created.

Grab and OLE DB Destination and drag it over. Connect it with the outbound arrow from the Derived Column box

Select the new dbo.STUDENT_TEAM_HIST table we created and next click on Mappings

You will see you now have four columns feeding into your new destination table. If you go back and look at your source table, you will see you still only have 3 columns there. The fourth column is the one we just derived.

Hit okay, now we are ready to run the package

Right click on Package and hit Execute Package

It should run. Notice the little comments telling you how many rows moved.

Go to SQL Server and check your new table. You will see the INSERT_DT

Okay, now to see the historical data in action

Let’s change Micah’s team from Red to Blue in our STUDENT_TEAM table

update [dbo].[STUDENT_TEAM]
set STUDENT_TEAM = 'Blue'
where STUDENT_NM = 'Micah'

select *
from dbo.STUDENT_TEAM

Go back to SSIS, hit the red box at the top to end debugging mode

Right click and execute the package again

Now run your query again. Note the two different teams Micah was on are listed. Along with the timestamps so you can tell when he was on which team.

SQL Query to build table from lesson 2

CREATE TABLE [dbo].[STUDENT_TEAM](
       [STUDENT_NM] [varchar](50) NULL,
       [STUDENT_AGE] [int] NULL,
       [STUDENT_TEAM] [varchar](50) NULL
)

insert into dbo.STUDENT_TEAM
       (STUDENT_NM, STUDENT_AGE, STUDENT_TEAM)
VALUES
       ('Bob', 15, 'Red'),
       ('Claire', 17, 'Blue'),
       ('Chris', 17, 'Blue'),
       ('Candice', 14, 'Red'),
       ('Holly', 16, 'Blue'),
       ('Micah',15,'Red'),
       ('Stephanie', 16, 'Blue'),
       ('Joshua', 14, 'Red'),
       ('Sherrie', 18, 'Blue')

SSIS: Lesson 2

Import data from CSV into database

In the first lesson we exported data from a table in our SQL Server database to a CSV file. Today we are going to do just the opposite, we are going to bring data from a CSV file into our database.

I like to try to provide close to real world scenarios when I make my tutorials. Obviously in the simpler intro lessons, that can be difficult. That being said, for this lesson, imagine you manage a database for a school. Every week 9 students are selected to be on either the Red Team (Hall Safety Monitors) or the Blue Team (Lunch Room Aids). Every Friday, the Vice Principal Smith picks the student names at random and puts them into a CSV file that is emailed out to all the teachers. You point out that if you could just get the names into your database, you could put the information on the school’s main Intranet page, so the teachers don’t need to download and open the same CSV file 300 times a week.

So our task is to upload the new weekly CSV file into the database every Friday at the end of the school day.

Here is this week’s CSV file:

Lesson_2

First, before heading into SSIS, we need to create a destination table in our database for the CSV file. Here is the file we want to import into our database, you’ll note it has three columns, two columns are strings and one is an integer:

So go into SSMS (SQL Server Management Studio) and run the following query to create the table:

CREATE TABLE STUDENT_TEAM (
 STUDENT_NM varchar(50),
 STUDENT_AGE int,
 STUDENT_TEAM varchar(50))
GO

This code will create an empty table with 3 columns named STUDENT_NM, STUDENT_AGE, STUDENT_TEAM.

Now you can minimize SSMS and open up Visual Studios Data Tools

Once open, go into your Training Project and create a new SSIS Package. I’m naming this one Lesson_2

Now grab an Execute SQL Task from the SSIS Toolbox and drag it to the Design window.

Notice the red arrow at the bottom, there is already a Connection set up for the Sandbox database. This is because when we made this connection in Lesson_1, we made it by clicking on the Connection Managers in the Solution Explorer window.

This creates a (Project) connection – one that can be seen in every package. If you only want your connection to exist inside a single package (this becomes important as the number of packages you have grows, otherwise you’d have thousands of connections in Solution Explorer) – you can right click anywhere inside the Connection Managers box at bottom of the design window.

But this particular package will work fine just using the existing connection, we can move on without creating a new one.

Double Click on your Execute SQL Task icon in the design window.

In the window that pops up, you can rename your Task, provide a description of the task if you would like. This does come in handy when you have to go back to old package. It makes it easier to understand what is going on.

Down at the green arrow in the picture, you’ll have to selection a Connection from the drop down. Luckily were currently only have one to choose from.

Next go to SQL Statement and click on the little ‘…’ box that appears in the right corner.

In the pop up window, this is where you enter your SQL Query. In this case were going to delete all data from table in this box. The reason for this step is so that last week’s students won’t still be in the table on Monday morning. We only want the current students in our database.

Now click Okay on this window and click OKAY again to get back to the Design Window

Next drag over a Data Flow Task. Connect the Create Table task by dragging the arrow over from the Create Table task. Note the direction of the arrow, this is the order in which tasks will run.

Now open Data Flow Task. In the SSIS Toolbox, go to Other Sources and drag a Flat File Source over to the Design Window.

Double click on your new Flat File Source box and a new window will open. Click on New… next to Flat File Connection Manager

On the new window, click Browse

Browse to your CSV File. I created a folder called SSIS Training to make it easy to store all my files.

If you click on Columns in the left window, you can see what the CSV file contains.

Finally, before existing this window, Click back on General and make sure Column names in the first data row is checked.

Now go back to the Design window and drag an OLE DB Destination box onto the design window. Connect the blue arrow from the Flat File Source to the OLE DB Destination

Now double click on OLE DB Destination

Select STUDENT_TEAM from Name of table or the view

Now Click on Mappings

Everything should line up nicely since we named the table columns to match the CSV file.

Now click okay to go back to the Design Window, Click on Control Flow in the upper left to get back to the main page of the package

Right click the package and click Execute Package

If all goes well, you should end up with two green checks

If this happens, check to make sure your CSV file is not currently open, that can cause errors. If so, close the file and try executing the package again

Finally, check the table in your SQL Server to see if it populated

If you want to see how it would work the next week, go into the CSV file and change the data. When you run the package again, the names in the SQL table will change too.