CASE statement if else Magic ETL

leeloo_dallas

Hey guys I am trying to fill a column based on certain criteria from 4 columns.

I think it would be best to do this in another column so that I'm not overwriting anything. 

My table looks like the following and I'm trying a Case Statement that fills in the null spaces, but I think my case statement is missing something or I'm missing a step. 

publish_date	date_created	time_created	date_updated	time_updated
04/30/2020	04/30/2020	18:37:06	04/30/2020	18:37:06
04/30/2020	04/30/2020	18:38:06	04/30/2020	18:38:06
	04/30/2020	17:09:29	04/30/2020	17:09:29
04/30/2020	04/30/2020	18:37:08	04/30/2020	18:43:11
	04/30/2020	19:06:07	04/30/2020	19:06:07
04/30/2020	04/30/2020	18:37:08	04/30/2020	18:43:11
	04/30/2020	12:00:33	04/30/2020	12:00:36
04/30/2020	04/30/2020	18:38:05	04/30/2020	22:31:32

 

My case statement looks like this so far:

CASE when `date_created`=`date_updated` and `time_created`=`time_updated` and `publish_date` IS NULL then `date_created` else `publish_date` end

Unfortunately my case statement sucks and this doesn't work to my advantage. 

 

Can anyone help?

GrantSmith

Hi @user052846 

You didn't clearly state what exactly your issue was with your beast mode so I'm somewhat guessing here but you're essentially wanting to use the most recent date between publish date and update date  for the publish date if the publish date is null correct?

 

If that's correct then you have two independent conditions dependent upon each other. Essentially you're saying the dates must be the same and publish date must be null in order for you to use the creation date.  I'm assuming here too that your creation date and updated date will be the same when an entry is created. With those assumptions you can just narrow down your beast mode to using the updated date if the publish date is null.

 

Simplifies down to:

IFNULL(`publish_date`, `date_updated`)

 

 

jaeW_at_Onyx

a series of nested IFNULL statements will get the job done as per Grant's recommendation, but have a look at COALESCE() it will return the first non null value in a chain.

 

if you want to write it as a case statement then do a series of null checks

 

case 

when colA is not null then colA

when colB is not null then colB

when colC is not null then colC

...

else ...

end

 

by definition you don't need to build extensive logic b/c in order for the second clause (test for to apply, colA must have been null (otherwise the preceeding logic step would have applied).