Problems with GROUP BY - not a GROUP BY expression

Question

Hello,
I am fighting little bit with GROUP BY expression.
After some tests I am able to reduce the problem to following...
When can I use column numbers in GROUP BY expression?
Consider this situation:
CREATE TABLE EMP4 (
   NAME VARCHAR2(10)
COMMIT;
INSERT INTO EMP4 VALUES('Tamara');
INSERT INTO EMP4 VALUES('John');
INSERT INTO EMP4 VALUES('Joseph');
COMMIT;
SELECT NAME, COUNT(*)
FROM EMP4
GROUP BY 1;
00979. 00000 -  "not a GROUP BY expression"
-- This is working
SELECT NAME, COUNT(*)
FROM EMP4
GROUP BY NAME;Why is the GROUP BY 1 not workig?
I am using the GROUP BY 1 because in real query there is some PL/SQL function which somehow modifies the column NAME, so I can't use the column name
SELECT TEST_PACKAGE.AppendSomeCharacter(NAME), COUNT(*)
FROM EMP4
GROUP BY 1;Of course I can nest the query and move the COUNT and GROUP BY to outer query or maybe something else, but I was just curious why is the GROUP BY not working...
Also in real query, there are 3 columns in the GROUP BY expression, so I have there GROUP BY 1, 2, 3
Thanks for help

Answer 1

hai
try the following
CREATE TABLE TBL(ID NUMBER,VAL VARCHAR(20));
INSERT INTO TBL VALUES(1,'Z');
INSERT INTO TBL VALUES(2,'X');
INSERT INTO TBL VALUES(1,'Z');
INSERT INTO TBL VALUES(2,'X');
INSERT INTO TBL VALUES(3,'A');
INSERT INTO TBL VALUES(4,'H');
INSERT INTO TBL VALUES(5,'B');
INSERT INTO TBL VALUES(6,'C');
INSERT INTO TBL VALUES(7,'T');
INSERT INTO TBL VALUES(3,'A');
INSERT INTO TBL VALUES(4,'H');
INSERT INTO TBL VALUES(5,'B');
INSERT INTO TBL VALUES(6,'C');
INSERT INTO TBL VALUES(7,'T');
CREATE TYPE SAMPLETYPE AS OBJECT ( ID NUMBER, NAME
VARCHAR2(25) ) ;
CREATE TYPE SAMPETBLTYPE AS TABLE OF SAMPLETYPE;
CREATE OR REPLACE FUNCTION SAMPLEFUNC
p_colname varchar2
)return SAMPETBLTYPE pipelined as
ret_val SAMPLETYPE;
TYPE cursor_ref IS REF CURSOR;
fcur cursor_ref;
di TBL%ROWTYPE;
sqlstr varchar2(1000);
colname varchar(30):=p_colname;
begin
sqlstr:='SELECT * FROM TBL ORDER BY '|| colname ;
DBMS_OUTPUT.PUT_LINE(sqlstr);
open fcur FOR sqlstr;
loop
FETCH fcur INTO di;
EXIT WHEN fcur%NOTFOUND;
ret_val:=SAMPLETYPE(di.ID,di.VAL);
PIPE ROW(ret_val);
end loop;
close fcur;
return;
end;     
select * from table(SAMPLEFUNC('ID'));
select * from table(SAMPLEFUNC('VAL'));