ETL Addition empty fields

user046467
user046467 ⚪️
in Dataflows

I am using addition to calculate 2 columns into a calculated column "Total 3".

 

Example:

 

Total 1 | Total 2 | Total 3

1 |  2 | 3

2 | 2  | 4

1 |    | 

4 | 1 |  5

 

Problem is I don't have data in every row. So as you can see the third one here results nothing instead of 1. 1 + "blank" is still 1.

But it returns an empty field.

 

Any solution to this in ETL?

Best Answer

  • GrantSmith
    GrantSmith Indiana 🔴
    Accepted Answer

    Hi @user046467 

    This is because how SQL works. When you add null to something the result is NULL.

     

    A couple of options:

     

    Beast Mode

    COALESCE(`Total 1`, 0) + COALESCE(`Total 2`, 0)

    MySQL ETL:

    Same code above in your select statement

     

    Magic ETL:

    Use a Value Mapper tile. Under step 4 - 'Enter a value to search for' click the gear icon and select Null Value. Put 0 in the step 5 - Enter a value to write

Answers

  • user046467
    user046467 ⚪️

    Thanks @GrantSmith !

     

    I am new to SQL so figuring everything out by trial and error.

    But this makes perfect sense so I will try this soon Smiley Happy

  • jaeW_at_Onyx
    jaeW_at_Onyx Budapest / Portland, OR 🟤

    do you actually need to calculate at the row level?

     

    could you just do

    SUM(colum1) + sum(column2) and get the desired result?

    In beast modes this will be faster performance than calculating at the row level b/c of how adrenaline works.

    but if you're concerned that SUM(column1) may end up being NULL, you could wrap it.

     

    coalesce(sum(column1),0) + coalesce(sum(column2),0).

     

    IFNULL may be easier to read but functionally does the same thing.  (i prefer coalesce).

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