How to Dynamically Update a Table's Set Name Based on Date Ranges Using a Case Statement?

Dynamic Case Statement for Update Using Split Dates and Sets

Problem:

Given two parameters, p_dates and p_sets, containing date ranges and set names respectively, the goal is to prepare a dynamic SQL case statement that updates a table's set_name column with the appropriate set name based on the given date range.

Solution:

1. Splitting Dates:

To split the p_dates parameter into individual date ranges, use the string_to_array() function with a comma (,) as the delimiter:

SELECT unnest(string_to_array(p_dates, ',')) AS date_range;

2. Splitting Sets:

Similarly, to split the p_sets parameter into individual set names, use the same technique:

SELECT unnest(string_to_array(p_sets, ',')) AS set_name;

3. Preparing Dynamic Case Statement:

Using the split dates and sets, concatenate them into a case statement dynamically:

CASE
  WHEN given_dates BETWEEN split_part(date_range, 'to', 1)::date
                     AND split_part(date_range, 'to', 2)::date
  THEN set_name
  ELSE NULL
END

Implementation:

To update the table_name table, use the following SQL statement:

UPDATE table_name
SET set_name = (
  CASE
    WHEN given_dates BETWEEN split_part(date_range, 'to', 1)::date
                           AND split_part(date_range, 'to', 2)::date
    THEN set_name
    ELSE NULL
  END
)
FROM split_dates
JOIN split_sets
  ON 1 = 1;

Benefits:

This dynamic approach allows for flexible updates based on changing parameters, eliminating the need for static case statements and providing a more versatile solution for date range and set manipulation.

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