1  CREATE OR replace PROCEDURE Validate_emp_id_yn
  2  IS
  3    CURSOR cu_emp_count(in_emp_id VARCHAR2) IS
  4      SELECT Count(*)
  5      FROM   emp
  6      WHERE  empno = in_emp_id;
  7    lv_count NUMBER;
  8    v_message varchar2(1000);
  9  BEGIN
 10      IF empno IS NULL THEN
 11        v_message:='empno error';
 12        dbms.output.put_line(v_message);
 13        RAISE form_trigger_failure;
 14      ELSE
 15        OPEN cu_emp_count(empno);
 16        FETCH cu_emp_count INTO lv_count;
 17        CLOSE cu_emp_count;
 18        IF ( lv_count > 0 ) THEN
 19          v_message:='empno error';
 20          dbms.output.put_line(v_message);
 21          RAISE form_trigger_failure;
 22        END IF;
 23      END IF;
 24* END;
SQL> /

Warning: Procedure created with compilation errors.

SQL> show error
Errors for PROCEDURE VALIDATE_EMP_ID_YN:

LINE/COL ERROR
-------- --------------------------------------------------
10/5     PL/SQL: Statement ignored
10/8     PLS-00201: identifier 'EMPNO' must be declared
SQL> 

dbms.output.put_line

dbms_output.put_line

  1  CREATE OR replace PROCEDURE Validate_emp_id_yn
  2  IS
  3    CURSOR cu_emp_count(v_empno number) IS
  4      SELECT Count(*)
  5      FROM   emp
  6      WHERE  empno = v_empno;
  7    lv_count NUMBER;
  8    v_empno emp.empno%type;
  9    v_message varchar2(1000);
 10  BEGIN
 11      IF v_empno IS NULL THEN
 12        v_message:='empno error';
 13        dbms_output.put_line(v_message);
 14      ELSE
 15        OPEN cu_emp_count(empno);
 16        FETCH cu_emp_count INTO lv_count;
 17        CLOSE cu_emp_count;
 18        IF ( lv_count > 0 ) THEN
 19          v_message:='empno error';
 20          dbms_output.put_line(v_message);
 21        END IF;
 22      END IF;
 23* END;
SQL> /

Warning: Procedure created with compilation errors.

SQL> show error
Errors for PROCEDURE VALIDATE_EMP_ID_YN:

LINE/COL ERROR
-------- --------------------------------------------------------------
15/7     PL/SQL: SQL Statement ignored
15/25    PLS-00201: identifier 'EMPNO' must be declared

OPEN cu_emp_count(empno);

OPEN cu_emp_count(v_empno);

SQL> CREATE OR REPLACE PROCEDURE VALIDATE_EMP_ID_YN(IN_EMP_ID NUMBER) AS
  2     CURSOR CU_EMP_COUNT(IN_EMP_ID VARCHAR2) IS
  3        SELECT COUNT(*) FROM EMP WHERE EMPNO = IN_EMP_ID;
  4     LV_COUNT  NUMBER;
  5     V_MESSAGE VARCHAR2(1000);
  6     EMP_NO    NUMBER;
  7  BEGIN
  8     IF IN_EMP_ID IS NULL THEN
  9        V_MESSAGE := 'empno error';
 10        DBMS_OUTPUT.PUT_LINE(V_MESSAGE);
 11        --RAISE FORM_TRIGGER_FAILURE;
 12     ELSE
 13        OPEN CU_EMP_COUNT(IN_EMP_ID);
 14        FETCH CU_EMP_COUNT
 15           INTO LV_COUNT;
 16        CLOSE CU_EMP_COUNT;
 17        IF (LV_COUNT > 0) THEN
 18           V_MESSAGE := 'empno error';
 19           DBMS_OUTPUT.PUT_LINE(V_MESSAGE);
 20           --RAISE FORM_TRIGGER_FAILURE;
 21        END IF;
 22     END IF;
 23  END;
 24  /
 
Procedure created
 
SQL> sho err;
No errors for PROCEDURE VALIDATE_EMP_ID_YN

SQL> set serveroutput on;
SQL> BEGIN
  2     VALIDATE_EMP_ID_YN(NULL);
  3     END;
  4  
  5  /
 
empno error
 
PL/SQL procedure successfully completed

CREATE OR REPLACE PROCEDURE validate_emp_id_yn(in_emp_id emp.empno%TYPE) AS

   lv_count  NUMBER;

BEGIN

  IF in_emp_id IS NULL THEN

    dbms_output.put_line('empno error');

  ELSE
 
    SELECT COUNT(*) INTO lv_count;
    FROM emp
    WHERE empno = in_emp_id;
    
    IF lv_count != 1 THEN

      dbms_output.put_line('empno error');

    END IF;

  END IF;

END;
/

Select 1 INTO lv_count;
    FROM emp
    WHERE empno = in_emp_id;

IF SQL%NOTFOUND then
    dbms_output.put_line('empno error');
end if;