每次插入一行时的SQL更新列

Question

Ok, so I have this table: VersionsEditor with id - bigint version - integer startdate- date endDate - date bookId - integer

My problem: When I insert a new row for a certain book the endDate value must be "In progress". So I think I can't have date as the column type.. The logic is when the I have the greatest version for a certain book, then the endDate must be "In progress"

Answer 1

Why would you use a date column for status? Instead, you want a another column for status. I might suggest a view:

create view v_book as
    select b.*,
           (case when startDate is null then 'NotStarted'
                 when endDate is null then 'InProgress'
                 else 'Done'
            end) as Status
    from books

Answer 2

What about Triggers (Oracle DB) like that ...

CREATE OR REPLACE TRIGGER t
  BEFORE
    INSERT OR
    UPDATE OF salary, department_id OR
    DELETE
  ON employees
BEGIN
  CASE
    WHEN INSERTING THEN
      DBMS_OUTPUT.PUT_LINE('Inserting');
    WHEN UPDATING('salary') THEN
      DBMS_OUTPUT.PUT_LINE('Updating salary');
    WHEN UPDATING('department_id') THEN
      DBMS_OUTPUT.PUT_LINE('Updating department ID');
    WHEN DELETING THEN
      DBMS_OUTPUT.PUT_LINE('Deleting');
  END CASE;
END;
/

Answer 3

A date should be a date and not an integer or varchar. If the meaning of "in progress" is that there cannot be any date specified, then just set it to null when in progress. You can query it thus:

select coalesce( to_char(enddate, 'DD-MM-YYYY') , 'In progress' ) as end_date
from mytable
where ...