is this possible? adding 4 new columns: createdDate,modifiedDate,createdBy,modifiedBy? - sql

Question

I'm on sql developer. I have a table. I Want to add those 4 new columns which I know how to do, but I want those values to not be entered by the user when he enters a new row or edits an existing row, I want those values to be automatically filled
For example if the user enters
insert into tableName values (val1,val2,val3)
then the table will have the 7 new values in the new row:
val1,val2,val3,createdDate,modifiedDate,createdBy,modifiedBy
same when the user modifies a value in an existing row
update TAbleName set val1 = newVal where id = id1
and then the "modifiedDate" and "modifiedBy" fields in that row will be automatically modified

Answer 1

What database do you use?
For auto fill when you add a new row, you need to setup "default binding" aka "default field"
ALTER TABLE YourTable
ADD CONSTRAINT DF_YourTable DEFAULT GETDATE() FOR YourColumn
For update, you need to make a trigger to edit the column
How to: Create trigger for auto update modified date with SQL Server 2008

Answer 2

Partially, column's default value can do that (for created date and user who did that); for modifications, use a trigger.
Here's an example:
SQL> create table test (id number, name varchar2(20));
Table created.
SQL> alter table test add
2 (created_date date default sysdate,
3 created_by varchar2(30) default user,
4 modified_date date,
5 modified_by varchar2(30)
6 );
Table altered.
SQL> insert into test (id, name) values (1, 'Little');
1 row created.
SQL> select * From test;
ID NAME CREATED_DATE CREATED_BY MODIFIED_DATE MODIFIED_B
---------- -------------------- ------------------- ---------- ------------------- ----------
1 Little 13.02.2020 22:23:17 SCOTT
Updating a row a little bit later - nothing has changed (for created and modified columns):
SQL> update test set name = 'Foot' where id = 1;
1 row updated.
SQL> select * From test;
ID NAME CREATED_DATE CREATED_BY MODIFIED_DATE MODIFIED_B
---------- -------------------- ------------------- ---------- ------------------- ----------
1 Foot 13.02.2020 22:23:17 SCOTT
Let's create a trigger. It's a simple one:
SQL> create or replace trigger trg_testmod_bu
2 before update on test
3 for each row
4 begin
5 :new.modified_date := sysdate;
6 :new.modified_by := user;
7 end;
8 /
Trigger created.
SQL> update test set name = 'Bigfoot' where id = 1;
1 row updated.
SQL> select * From test;
ID NAME CREATED_DATE CREATED_BY MODIFIED_DATE MODIFIED_B
---------- -------------------- ------------------- ---------- ------------------- ----------
1 Bigfoot 13.02.2020 22:23:17 SCOTT 13.02.2020 22:26:38 SCOTT
Right; the trigger updated both modified columns.