Realized Netezza, and Amazon redshift are two different systems

Connecting to Amazon redshift using Netezza Aginity. 

Want to complete the following: 

We have a column of strings in a table in Netezza. 

The strings have some underscores. we want to do the following, if a string has more than 10 underscores, we want to get the substring between the 1st and second underscore.

I planed to use the following one:

SELECT str,
case when len(str)-len(replace(str,'_','')) >10 
then 

substring(str,dlim1+1,(dlim2-dlim1)-1) as column2,

end

And 

set dlim1 = charindex('_',str)set dlim2 = charindex('_',str,charindex('_',str)+1)

But it did not work. And I used instr, still not working.

And I found Amazon redshift has the following function:

http://docs.aws.amazon.com/redshift/latest/dg/REGEXP_INSTR.html

And it works. 

And here is another function:

http://docs.aws.amazon.com/redshift/latest/dg/SPLIT_PART.html


They both work.