How to to identify and fetch a fixed value from a fixed column across the Oracle DB 11g

Question

Hi i have a requirement to find and identify a specific value from a fixed column across DWH schemas,ideally in order to identify the system name associated to each number so that i can track the total count of tables associated to that system an example will give a clear understanding

Let's consider i have some 100 systems starting from 1 to 100 numbers so each system is defined by a number

example

SYSTEM NO
LOGISTIC 1
FINANCE 2
SALES 3
CREDIT 4
SECUTIRY 5

and soo on untill 100

in DB i have some thousands of tables so each table will have s fixed column called ETL_SOURCE_SYSTEM which will have this number defined so that there will be a metadata static table/lookup table which will hold the system name and it's associated system no, so not that the system and system no is unique

so now i need to come up with a dynamic sql in order to scan through all the schemas in DWH in order to identify which system name and number have the total counts across all the schemas from all the tables

Query

select * from dba_tab_cols
where column_name like '%ETL_SOURCE_SYSTEM%'

Query - New Idea

select 'with tmp(schema_name,table_name, system_nbr) as (' from dual 
union all 
select 'select '''||owner||'''''as SCHEMA_NAME'','''||object_name||'''''as TABLE_NAME'',ETL_SOURCE_SYSTEM from '||object_name||' union all ' from dba_objects 
where owner not in ('EXCLUDE the some of the nor relevant schemas like SYS,PUBLIC..')
--and owner=''
and object_type ='TABLE'
union all
select 'select '''','''',0 from dual) select owner,table_name,system_nbr from tmp order by owner,system_nbr desc ;' from dual; 

If this is really possible to in dynamic sql in order to fetch the value system no 1 to 100 from all the tables in order to get the below desired result

Expected results

SCHEMA_NAME TOTAL_COUNTS_OF_TABLES SYSTEM_NAME SYSTEM_NUMBER 
STAGE       150                    LOGISTIC    1
EDW         300                    LOGISTIC    1
MART        600                    LOGISTIC    1
STAGE       150                    FINANCE     2
EDW         300                    FINANCE     2
MART        600                    FINANCE     2
STAGE       150                    SALES       3
EDW         300                    SALES       3
MART        600                    SALES       3
STAGE       150                    CREDIT      4
EDW         300                    CREDIT      4
MART        600                    CREDIT      4

Note: DB is Oracle 11g and i have only covered few schemas for an example the schema list is big 50+ or more

any suggestions?

Answer 1

Dynamic SQL it is, as you presumed. Here's an example which shows how to do it. I presume you'll have to modify it a little bit (or a little bit more), but the principle should be OK.

For simplicity, I'm just displaying the output to the screen. If you want to do it differently, for example using a function which would return a collection or a refcursor, do so.

Read comments within code.

SQL> declare
  2    l_cnt number;         -- number of tables in each schema
  3    l_tab varchar2(30);   -- one (any; I chose MAX) table in each schema, as all of them contain ETL_SOURCE_SYSTEM column
  4    l_ess number;         -- value of ETL_SOURCE_SYSTEM in L_TAB table
  5    l_sys varchar2(20);   -- system name
  6    l_out varchar2(200);  -- output string
  7  begin
  8    -- display header
  9    dbms_output.put_line('Schema      Tabs   System     ESS' ||chr(10) ||
 10                            '----------- ----   ---------- ---');
 11    -- loop through all users; I'm using only two users in my database
 12    for cur_r in (select username from dba_users
 13                  where username in ('MICHAEL', 'SCOTT')
 14                 )
 15    loop
 16      -- pick any (I chose MAX) table name and count of tables for each schema
 17      execute immediate 'select max(table_name), count(*) from dba_tables where owner = ' ||
 18        chr(39) || cur_r.username || chr(39)
 19        into l_tab, l_cnt;
 20
 21      -- fetch ETL_SOURCE_SYSTEM value in that schema
 22      execute immediate 'select etl_source_system from ' || cur_r.username ||'.'|| l_tab into l_ess;
 23
 24      -- find system name in the lookup table (located in schema I use to run this code; should
 25      -- be a privileged user which has access to DBA_ views
 26      select system
 27        into l_sys
 28        from t_lookup
 29        where etl_source_system = l_ess;
 30
 31      -- compose the output string
 32      l_out := rpad(cur_r.username, 12, ' ') || to_char(l_cnt, '990') || '   ' ||
 33               rpad(l_sys         , 10, ' ') || to_char(l_ess, '990');
 34
 35      -- display the result
 36      dbms_output.put_line(l_out);
 37
 38    end loop;
 39  end;
 40  /
Schema      Tabs   System     ESS
----------- ----   ---------- ---
SCOTT         30   LOGISTIC     1
MICHAEL       27   FINANCE      2

PL/SQL procedure successfully completed.

SQL>