In oracle database, I have a table stored TASK_ID, TASK_START_DATE, TASK_END_DATE. How do I create a table with each row showing TASK_ID and DATE? (DATE being each day from start til end)
| TASK_ID | TASK_START_DATE | TASK_END_DATE | 
|---|---|---|
| 001 | 03-04-2021 | 05-04-2021 | 
| 002 | 05-04-2021 | 07-04-2021 | 
To
| TASK_ID | DATE | 
|---|---|
| 001 | 03-04-2021 | 
| 001 | 04-04-2021 | 
| 001 | 05-04-2021 | 
| 002 | 05-04-2021 | 
| 002 | 06-04-2021 | 
| 002 | 07-04-2021 | 
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Answer
Date and time functions are notoriously database dependent. However, in standard SQL, you can approach this using a recursive CTE:
with recursive dates as (
      select TASK_ID, TASK_START_DATE, TASK_END_DATE
      from t
      union all
      select TASK_ID, TASK_START_DATE + INTERVAL '1' DAY, TASK_END_DATE
      from dates
      where TASK_START_DATE < TASK_END_DATE
     )
select task_id, task_start_date
from cte;
Note that this suggests and approach. The specific syntax depends on the database you are using.