INSERT and UPDATE a record using cursors in oracle

Question

I have 2 tables- student and studLoad both having 2 fields studID and studName. I want to load data from student

Answer 1

This is a highly inefficient way of doing it. You can use the merge statement and then there's no need for cursors, looping or (if you can do without) PL/SQL.

MERGE INTO studLoad l
USING ( SELECT studId, studName FROM student ) s
ON (l.studId = s.studId)
WHEN MATCHED THEN
  UPDATE SET l.studName = s.studName
   WHERE l.studName != s.studName
WHEN NOT MATCHED THEN 
INSERT (l.studID, l.studName)
VALUES (s.studId, s.studName)

Make sure you commit, once completed, in order to be able to see this in the database.

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To actually answer your question I would do it something like as follows. This has the benefit of doing most of the work in SQL and only updating based on the rowid, a unique address in the table.

It declares a type, which you place the data within in bulk, 10,000 rows at a time. Then processes these rows individually.

However, as I say this will not be as efficient as merge.

declare

   cursor c_data is
    select b.rowid as rid, a.studId, a.studName
      from student a
      left outer join studLoad b
        on a.studId = b.studId
       and a.studName <> b.studName
           ;

   type t__data is table of c_data%rowtype index by binary_integer;
   t_data t__data;

begin

   open c_data;
   loop
      fetch c_data bulk collect into t_data limit 10000;

      exit when t_data.count = 0;

      for idx in t_data.first .. t_data.last loop
         if t_data(idx).rid is null then
            insert into studLoad (studId, studName)
            values (t_data(idx).studId, t_data(idx).studName);
         else
            update studLoad
               set studName = t_data(idx).studName
             where rowid = t_data(idx).rid
                   ;
         end if;
      end loop;

   end loop;
   close c_data;

end;
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