Display message if table is empty - oracle

Question

I have a table and if data exists I have to display data with dbms_output. If the table is empty I have to write a message "table is empty'.
I want to use cursors and I don't know how the condition should look like when the table is empty.
That works fine:
declare
cursor cursor_name is select nr, name from branch;
begin
for i in cursor_name
loop
dbms_output.put_line('Number: ' || to_char(i.nr) || ' Name: ' || i.name);
end loop;
end;
/

Answer 1

Just use a variable to store a flag which you can set if rows are found:
DECLARE
CURSOR cursor_name IS
SELECT nr, name FROM branch;
no_rows BOOLEAN := TRUE;
BEGIN
FOR i IN cursor_name LOOP
DBMS_OUTPUT.PUT_LINE('Number: ' || to_char(i.nr) || ' Name: ' || i.name);
no_rows := FALSE;
END LOOP;
IF no_rows THEN
DBMS_OUTPUT.PUT_LINE('Table is empty');
END IF;
END;
/
Or:
DECLARE
CURSOR cursor_name IS
SELECT nr, name FROM branch;
cursor_row cursor_name%ROWTYPE;
BEGIN
OPEN cursor_name;
FETCH cursor_name INTO cursor_row;
IF cursor_name%NOTFOUND THEN
DBMS_OUTPUT.PUT_LINE('Table is empty');
END IF;
LOOP
EXIT WHEN cursor_name%NOTFOUND;
DBMS_OUTPUT.PUT_LINE(
'Number: ' || to_char(cursor_row.nr) || ' Name: ' || cursor_row.name
);
FETCH cursor_name INTO cursor_row;
END LOOP;
CLOSE cursor_name;
END;
/
Which, for the sample data:
CREATE TABLE branch (nr, name) AS
SELECT 1, 'Aspen' FROM DUAL UNION ALL
SELECT 2, 'Beech' FROM DUAL UNION ALL
SELECT 3, 'Cedar' FROM DUAL;
Both output:
Number: 1 Name: Aspen
Number: 2 Name: Beech
Number: 3 Name: Cedar
and after:
DELETE FROM branch;
Both output:
Table is empty
db<>fiddle here

Answer 2

You can use such a simple code block
SQL> SET serveroutput ON
SQL> DECLARE
v_mes VARCHAR2(50);
BEGIN
SELECT DECODE(COUNT(*),0,'Table is empty')
INTO v_mes
FROM t;
DBMS_OUTPUT.PUT_LINE(v_mes);
END;
/
if your aim is displaying only for the case that the table has no data

Answer 3

If you want to use a cursor, then this might be one option:
SQL> set serveroutput on;
Creating an empty table:
SQL> create table branch (nr number, name varchar2(20));
Table created.
Anonymous PL/SQL block: declare a cursor and its variable, fetch, check whether anything has been found:
SQL> declare
2 cursor c1 is select nr, name from branch;
3 c1r c1%rowtype;
4 begin
5 open c1;
6 fetch c1 into c1r;
7 if c1%notfound then
8 dbms_output.put_line('Table is empty');
9 end if;
10 close c1;
11 end;
12 /
Table is empty --> as expected
PL/SQL procedure successfully completed.
SQL>

Answer 4

Integrated solution using a database view - use with cursor and dbms_outputas you like:
create view v_branch as
select nr, name from branch
union all
select null, 'Table is empty' name from dual
where 0 = (select count(*) from branch);
select * from v_branch;
NR NAME
---------- --------------
1 x
delete from branch;
select * from v_branch;
NR NAME
---------- --------------
Table is empty
You will not want to use this for a very large tables - but it works fine for tables where you intend to print every row with put_line.