Understanding Control Columns in Data

A control column is a field or data column that functions as the main column for a data table.  Its main purpose is to determine the size of a table.  Therefore, the control column should always contain a value for each row or record.

The table below represents a data table for Date Assigned, Name, and Gender.  These three columns are also called fields.

Data table with control column

We designated Date Assigned as the control column.  In this case, a date value is assigned for each row.  When entering data, people may not always include a value for Gender.  On the other hand, everyone has a name, but it is easier to have dates as the control column.


Control Column Order

Now, the control column does not need to be the first column.  Place it in any position you choose.  The table below shows Date Assigned as the second column.

Data table with repositioned control column

Keep in mind, you can still perform the same calculations and determine the size of a table regardless of where you position the control column.

Duplicate Data

Data table with control column and duplicate data

If you noticed, the first two values of Date Assigned are duplicates.  That is okay.  With control columns, we are more concerned about the structure.  The data itself helps us with the analysis.

Control Columns versus Primary Keys

Control columns and primary keys are similar.  They both play a pivotal part of how you use and analyze data.  In this case, the difference is that primary keys assign unique values to a field.  Most of the time, these values are assigned automatically.

Primary keys generally help with maintaining data integrity and ensuring there are no duplicate records in a table.  They are not necessarily used as lookup values.

Using control columns is more about determining the size of a table, with data that you will also use as lookup values and for analytical purposes.

Optional Rule for Control Columns

An optional rule for control columns involves sorting the values in ascending or descending order.  Of course, this depends on the data.

Data table with sorted control column

We sorted the Date Assigned column in ascending order.  In the long run, this will help us group the data and perform calculations faster.

Overall, control columns will assist you in organizing your data and developing analytical summaries.

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