Case Statement with multiple conditions and excluding null values

I am trying to create a case statement where I have a new column that replaces a value in column1 with a value from column 2 but only if column 2 is not null. If it is null, then the value in column1 needs to remain the same.

Sample table:

I need it to look like this:


So "Account A" is replaced with "name" from column 2 when it is available.

I have tried this but it is not working:

(CASE 

 when

`Column2`is not null 

and `Column1`= 'Account A'

then `Column2`

else `Column1`

End)

What am I doing wrong?

Best Answer

  • MarkSnodgrass
    MarkSnodgrass Portland, Oregon 🥷
    Answer ✓

    If you're only wanting this to process for Account A, I would a nested case statement like this:

    (CASE WHEN TRIM(`column1`) = 'Account A' THEN
    (CASE WHEN TRIM(`column2`) = '' THEN `column1`
    ELSE `column2`
    END)
    ELSE `column1`
    END)
    


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Answers

  • MarkSnodgrass
    MarkSnodgrass Portland, Oregon 🥷

    Try just doing this:

    IFNULL(column2,column1)

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  • Thank you. That does not seem to give me the correct result because if column 2 is blank, then it is showing blank in the new column.

  • MarkSnodgrass
    MarkSnodgrass Portland, Oregon 🥷

    Blanks and nulls are not the same, so the ifnull function would not help with this data. I would try this to look for blanks:

    (CASE WHEN TRIM(`column2`) = '' THEN `column1`
    ELSE `column2`
    END)
    

    The trim function removes any spaces that may be in the data and then you can evaluate it to see if it is blank.

    Hope this helps.

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  • Thank you! I am getting closer...the first two rows are displaying correctly now, but now Account B is also being replaced with the name field, so how do I prevent that from happening?

  • That worked, thank you!