One of the most common tasks in any ETL project is converting data types.  When data begins in the form of a text file or (even worse) a formatted excel file, one often has to load the data as text fields initially and convert to proper data types after parsing out the relevant data.

Thankfully Alteryx has a lot of built in features to facilitate this.  One is the Multi-Field tool of which I gave an overview in my earlier post.  This handy tool lets you apply the same function across a whole set of columns without having to laboriously replicate it separately for each column as you must do in SQL select statements.

In many cases, however, one doesn’t even need to use any explicit data conversion tool in Alteryx – instead, you can just use the handy select tool which let’s you easily specify the data type you want while also allowing you to rename fields.  In the screenshot below, I’m using a select tool to convert generic field names (i.e. Field_1, Field_2, etc.) into more descriptive fields while at the same time converting them to the desired data type.

While this tool works great most of the time, one always seems to run into a catch eventually as I did the other day.  I was trying to load some data from CSV files that had extremely precise numbers stored as text (such as “53.534859348793489433498”).  When I tried to use the simple select tool to convert these text fields to numbers, I received an error message at run time that the field I was trying to convert “had more precision than a double. Some precision was lost.”

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