ORA-00972: identifier is too long ORA-06512 - oracle11g

Question

i have a PROCEDURE like this, whenever i execute the procedure it will give result in cursor according select type:
create or replace PROCEDURE EMAT_PROC_DROPDOWN_SELECTALL(SELECT_TYPE IN VARCHAR2, RESULT_SET OUT SYS_REFCURSOR)
AS
SELECT_TYPE_IN VARCHAR2(100);
TABLE_NAME VARCHAR2(100);
FIELD_NAME VARCHAR2(100);
C_ZONE SYS_REFCURSOR;
C_USER_ID SYS_REFCURSOR;
BEGIN
SELECT_TYPE_IN:=SELECT_TYPE;
IF(SELECT_TYPE_IN ='ZONE') THEN
BEGIN
TABLE_NAME:='MM_ZONEMASTER';
FIELD_NAME:='ZONE_NAME';
OPEN C_ZONE FOR
'SELECT DISTINCT' ||FIELD_NAME|| 'FROM' ||TABLE_NAME||';';
LOOP
FETCH C_ZONE INTO RESULT_SET;
EXIT WHEN C_ZONE%NOTFOUND;
END LOOP;
CLOSE C_ZONE;
END;
ELSIF(SELECT_TYPE_IN ='USER') THEN
BEGIN
TABLE_NAME:='AD_USERMASTER';
FIELD_NAME:='USER_ID';
OPEN C_USER_ID FOR
'SELECT DISTINCT' ||FIELD_NAME|| 'FROM' ||TABLE_NAME||';';
LOOP
FETCH C_USER_ID INTO RESULT_SET;
EXIT WHEN C_USER_ID%NOTFOUND;
END LOOP;
CLOSE C_ZONE;
END;
END IF;
END;
but the returns the error ***ORA-00972: identifier is too long
ORA-06512: at "EMAT.EMAT_PROC_DROPDOWN_SELECTALL", line 14
ORA-06512: at line 7

Answer 1

This is the issue: 'SELECT DISTINCT' ||FIELD_NAME|| 'FROM' ||TABLE_NAME||';';
It will see it as SELECT DISTINCTZONE_NAMEFROMMM_ZONEMASTER
The same goes for the other one.
Add spaces and write it as SELECT DISTINCT ' ||FIELD_NAME|| ' FROM ' ||TABLE_NAME||';';

Answer 2

There are missing space in the cursor around the field name and the table name. It reads SELECT DISTINCTZONE_NAMEFROMMM_ZONEMASTER; instead of SELECT DISTINCT ZONE_NAME FROM MM_ZONEMASTER;
Replace that line by this should help :
'SELECT DISTINCT ' ||FIELD_NAME|| ' FROM ' ||TABLE_NAME||';';
Additionally be careful with the use of nested blocks in your IF. I would avoid abusing from it if it's not needed.