How to Efficiently Split and Use Input Strings for Dynamic Case Statements?

Splitting Input Strings

To split the input strings (dates and sets), we can use the following techniques:

1. Dates (p_dates): Use the string_to_array() function to create an array of date ranges from the dates string. For example:

   SELECT string_to_array('2001-01-01to2001-01-05,2001-01-10to2001-01-15', ',')

2. Sets (p_sets): Similarly, use the string_to_array() function to split the sets string into an array of set names. For example:

   SELECT string_to_array('s1,s2,s3,s4', ',')

Preparing Dynamic Case Statement

Once these arrays are created, we can use them to generate the dynamic case statement using a combination of CASE WHEN and SELECT statements. For example:

CASE WHEN given_dates BETWEEN date_ranges[1] AND date_ranges[2] THEN set_names[1]
     WHEN given_dates BETWEEN date_ranges[3] AND date_ranges[4] THEN set_names[2]
     ...
     ELSE NULL
END

Here, date_ranges and set_names are the arrays created from p_dates and p_sets respectively.

This dynamic case statement can then be used to update the set_name column based on the specified date ranges and set names.

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