Tag Archives: ORA-00904

Return NULL if the column does not exist

It is a very common challenge for a dba to create scripts that work on every version.

How do you return NULL if a column does not exists?

Imagine I have a view that returns the table_name, column_name and retention_type of my LOBS.


SQL> create table t1(c clob) lob(c) store as (retention);

Table created.

SQL> create table t2(c clob) lob(c) store as (pctversion 10);

Table created.

SQL> create or replace force view v as select table_name,
  column_name,retention_type from user_lobs;

View created.

SQL> select * from v where table_name in ('T1','T2');
TAB COL RETENTION_TYPE
--- --- --------------
T1  C   YES
T2  C   NO

Let’s imagine I try to run this on an antique version of Oracle


SQL> select version from v$instance;
VERSION
-----------------
11.2.0.1.0

SQL> create table t1(c clob) lob(c) store as (retention);

Table created.

SQL> create table t2(c clob) lob(c) store as (pctversion 10);

Table created.

SQL> create or replace force view v as select table_name,column_name,retention_type from user_lobs;

Warning: View created with compilation errors.

SQL> select * from v where table_name in ('T1','T2');
select * from v where table_name in ('T1','T2')
              *
ERROR at line 1:
ORA-04063: view "SCOTT.V" has errors

Obviously the RETENTION_TYPE did not exist in that version.

Let’s default this to NULL !


SQL> create or replace function retention_type return varchar2 is 
  begin return null; end;
/

Function created.

SQL> select * from v where table_name in ('T1','T2');
TAB COL RETENTION_TYPE
--- --- --------------
T1  C
T2  C

Very simple workaround, is not it?