Add bitmap for NULLs in Oracle SQL

Question

I have the following table:

Table1

USER_ID     NAME    AGE     GENDER  ZIP_CODE
1           John    33      M       01086       
2           NULL    22      M       01247
3           Brown   NULL    F       01581

I want to add a bitmap as a column at the end.

USER_ID     NAME    AGE     GENDER  ZIP_CODE   NULL_COLUMN
1           John    33      M       01086      00000
2           NULL    22      M       01247      01000
3           Brown   NULL    F       01581      00100

The logic is

If value other than NULL, assign 0

If value = NULL, assign 1

Also, if I make a column NULL, then it needs to update the NULL_COLUMN, in the following way:

Update table1 set name = NULL;

Table1

USER_ID     NAME    AGE     GENDER  ZIP_CODE   NULL_COLUMN
1           NULL    33      M       01086      01000
2           NULL    22      M       01247      01000
3           NULL    NULL    F       01581      01100

Is there a way in Oracle SQL to create the NULL_COLUMN using the conditions and update it as the values become NULL?

Answer 1

You can use a generated column:

alter table table1
    add null_map generated always as (nvl2(userJ_id, '1', '0') || nvl2(name, '1', '0') || nvl2(age, '1', '') || nvl2(gender, '1', '') || nvl2(zip_code, '1', '0'));

Answer 2

You could use a concat for NVL2

select USER_ID 
,NAME
,AGE
,GENDE
,ZIP_CODE
, '0' || NVL2( NAME, '1', '0' ) || 
  NVL2( AGE, '1', '0' ) ||
  NVL2( GENDER, '1', '0' ) || 
  NVL2( ZIP_CODE, '1', '0' ) NULL_COLUMN

from my_table