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

@JonScott, @AlexYes and other pals who struggle with similar kinda situations.

I found more better approach other than suggested by @AlexYes.

What I did, I flatter category column which result individual records. Which I can further process.

Query:

select row_number() over(order by 1) as r1, 
        to_char(timestamptz 'epoch' + date_time * interval '1 second', 'yyyy-mm-dd') AS DAY,
        split_part(categories, ';', numbers.n) as catg,
        value
    from 
    join numbers
    on numbers.n <= regexp_count(category_string, ';') + 1 


Explanation:

Two functions are useful here: first, the split_part function, which takes a string, splits it on ';' delimiter, and returns the first, second, ... , nth value specified from the split string; second, regexp_count, which tells us how many times a particular pattern is found in our string.
    

             

                                                        
            
            

              
                
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