Question

I am new to oracle so not sure about how to write stored procedure in oracle. Currently I am googling and reading some articles/blogs on net on SP’s in oracle. I am begining to get some ideas about it. Even then I have following few queries.

What I am trying to do is,

I have a Employee table with emp_id, Region, Division, Product, Title etc.

I also have emp_update table with emp_id, column (what is changed), old_value, new_value and date.

e.g. emp_update table will have a row for for emp_id = 10, which says region is changed from Asia to UK on 30 April.

Another row for same emp which says product changed from A to B on 30 April.

So, multiple entries for same employee and on same date.

Now on that particular date I am running a cron job which will run this Sp to update employee table to these updates.

e.g. On date 30 April, update employee set region = UK, Product = B where emp_id = 10.

I want to run a single update statement for a employee with all its updates from emp_update table on that date.

So basically,

get all employees from emp_update with update on today.
iterate over that employees updates, assembple them in a single update statement and then execute that update query.
repeat for each employee.

Please help

EDIT 1:-

    CREATE OR REPLACE
PROCEDURE SP_RUN_EMPLOYEE_UPDATES 
IS


 CURSOR 
    c_emp 
 IS
    SELECT DISTINCT(employee_id) as employee_id FROM BI_EMPLOYEE_UPDATE WHERE EFFECTIVE_DATE = to_date('30-Apr-2012','dd-mm-yy');

BEGIN

FOR employee in c_emp

  LOOP

    CURSOR 
        c_emp_update 
    IS
      SELECT * FROM BI_EMPLOYEE_UPDATE WHERE employee_id = :employee.employee_id AND EFFECTIVE_DATE = to_date('30-Apr-2012','dd-mm-yy');

    FOR emp_update in c_emp_update
    LOOP



  --      dbms_output.put_line(emp_update.column_name);
    END LOOP;

  END LOOP;

END;

Currently this is what I have done so far

Answer 1

This question seems to be less about stored procedures and more about creating dynamic queries. Basically, you want this:

1. Cron job calls stored procedure
2. Proc will iterate over the records in emp_update with today’s date, sorted by employee_id
3. You will start building a dynamic SQL for the set expression of the update statement based off the values from the query. Simply “COLUMN_NAME = NEW_VALUE,” concatenated over and over for each column for that employee_id/date combination.
4. Build your SQL with the template UPDATE EMP SET <previous string here> WHERE EMPLOYEE_ID = <emp_id>.
5. Execute dynamic update sql