Question

Can I do something like the following in PLSQL?

if (some_query) then
    dbms_output.put_line('Your query returned at least 1 row.');
else
    dbms_output.put_line('Your query returned no rows.');
end if;

My use case is I want to check if a value already exists in my database. If the value already exists then I will do something different than if the value doesn’t exist at all.

Answer 1

If you a checking for existence of a record, then you can select COUNT(*) from the source table based on the key as it will always return a value you can check:

SQL> set serverout on
SQL> DECLARE
  2      v_check NUMBER;
  3  BEGIN
  4      SELECT COUNT(*)
  5      INTO v_check
  6      FROM DUAL
  7      WHERE DUMMY = 'X'
  8      AND ROWNUM = 1;
  9
 10      if (v_check = 0) then
 11          dbms_output.put_line('Your query returned no rows.');
 12      else
 13          dbms_output.put_line('Your query returned at least 1 row.');
 14      end if;
 15  END;
 16  /
Your query returned at least 1 row.

PL/SQL procedure successfully completed.

SQL>