How to get substring for filter and group by clause in AWS Redshift database

Question

How to get substring from column which contains records for filter and group by clause in AWS Redshift database.

I have table with records like:

Table_Id         


        

Answer 1

To do this fully dynamically, you need to transpose or pivot values in "categories" column into separate rows. Unfortunately, a "fully dynamic" solution (without knowing the different values beforehand) is NOT possible using redshift.

Your options are as follows:

1. Use the method suggested by AlexYes in another answer. This is semi-dynamic and is probably your best option.

2. Outside of Redshift, run some ETL code to perform the column -> multiple rows ETL.

3. Create a hardcoded type solution, and perform the pivot something like this:

   select table_id,'ABC1' as category, case when concat(Categories,';') ilike '%ABC1;%' then value else 0 end as value from your_table union all select table_id,'ABC1-1' as category, case when concat(Categories,';')ilike '%ABC1-1;%' then value else 0 end as value from your_table union all

etc