CODEWITHSUNDEEP
oracle-databaseplsql
Phoenix
Phoenix

Reputation: 1931

IF NOT EXISTS In Function PLSQL

I have a function which has three If/Then statements before opening a cursor. The If/Then statements check validity prior to opening the cursor.

I would like to add one more If/Then validity check, however, it is a bit more complicated than the others. Below is a sample, and I have block commented what I would like to add:

begin
    if not procedure.validation_function (<variable>, <condition>=TRUE) then
        return variable2;
    end if;

   /* if not exists
    (
       SELECT 'x' FROM table1
       WHERE table1_id = variable1_id
       AND trunc(sysdate) < trunc(table1_date + 60)
    ) then
        return variable2;
    end if; */

    open cursor(<argument>);
    fetch cursor into <variable>;
    close cursor;
    return <variable>;


end;

My problem is that I come from a T-SQL world, and I am finding in PL/SQL the if not exists command does not work. Is there a way I can, from within the function, have an If NO_DATA_FOUND statement where I utilize SELECT?

Is there a way to nest another function within that, so I can:

begin
     SELECT ....
     FROM ....
     WHERE ....
        if NO_DATA_FOUND then
           return variable2;
        end if;
end;

Upvotes: 8

Views: 48271

Answers (1)

Nick Krasnov
Nick Krasnov

Reputation: 27251

Exists condition can be used only in SQL statement, it cannot be used directly in PL/SQL. There are several options:

  • Using case expression with exists condition inside a select statement:

    SQL> declare
  2    l_exists number(1);
  3  begin
  4    select case
  5             when exists(select 1
  6                           from employees
  7                          where department_id = 1)
  8             then 1
  9             else 0
 10           end into l_exists
 11      from dual;
 12  
 13     if (l_exists = 1)
 14     then
 15       dbms_output.put_line('exists');
 16     else
 17       dbms_output.put_line(q'[doesn't exist]');
 18     end if;
 19  end;
 20  /

 doesn't exist

 PL/SQL procedure successfully completed

  • Or (rownum is needed to guarantee that the only one record will be returned if there are several records meet matching condition):

    SQL> declare
  2    l_exists number;
  3  begin
  4  
  5    select 1
  6      into l_exists
  7      from employees
  8     where department_id = 100
  9       and rownum = 1;
 10  
 11     dbms_output.put_line('exists');
 12  
 13  exception
 14    when no_data_found
 15    then dbms_output.put_line(q'[doesn't exist]');
 16  end;
 17  /

 exists

 PL/SQL procedure successfully completed

Upvotes: 10

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