Question

I have a table

CREATE TABLE STUDENT
(
  ID            INTEGER PRIMARY KEY,
  FIRSTNAME     VARCHAR2(1024 CHAR),
  LASTNAME      VARCHAR2(1024 CHAR),
  MODIFIEDDATE  DATE  DEFAULT sysdate
)

I am inserting a row of data

insert into STUDENT (ID, FIRSTNAME, LASTNAME, MODIFIEDDATE)  values (1,'Scott', 'Tiger', sysdate);

When I have to insert a record of data, I need to write a procedure or function which does the following:

1. if there is no record for the same id insert the row.
2. if there is a record for the same id and data matches then do nothing.
3. if there is a record for the same id but data does not match then update the data.

I am new to oracle. From the java end, It is possible to select the record by id and then update that record, but that would make 2 database calls. just to avoid that I am trying update the table using a procedure. If the same can be done in a single database call please mention.

Answer 1

For a single SQL statement solution, you can try to use the MERGE statement, as described in this answer https://stackoverflow.com/a/237328/176569

e.g.

create or replace procedure insert_or_update_student(
p_id number, p_firstname varchar2, p_lastname varchar2
) as
begin
    merge into student st using dual on (id = p_id)
         when not matched then insert (id, firstname, lastname) 
           values (p_id, p_firstname, p_lastname)
         when matched then update set 
           firstname = p_firstname, lastname = p_lastname, modifiedate = SYSDATE
end insert_or_update_student;