declare
    aocode varchar2(40);
    miscode varchar2(40);
    company varchar2(40);
    
begin

   select excoteamcode, excoaocode, companycode into miscode, aocode, company from mpr_setup where rownum = 1;
  
   SELECT      custaccountid,  CustNo, a.AccountNo, AccountName, Sector, SubSector, a.teamcode, a.accountofficercode, a.ProductCode, BranchCode, Currency, DateOpened, 
                         MaturityDate, Status, IsDormant, IsJoint, AccountType, SettlementAcct, CompanyCode
                         , (case a.Teamcode when null then miscode else to_char(a.Teamcode) end ) TeamCodeTemp 
                        ,(case a.accountofficercode when null then to_char(aocode) else to_char(a.accountofficercode) end ) AccountOfficerCodeTemp
                        , ContractRate, Active, Deleted, 
                         CreatedBy, CreatedOn, UpdatedBy, UpdatedOn, RowVersion

FROM            mpr_customer_account a;


end;

 select excoteamcode, excoaocode, companycode into miscode, aocode, company from mpr_setup where rownum = 1;

SELECT a.custaccountid,
       a.custno,
       a.accountno,
       a.accountname,
       a.sector,
       a.subsector,
       a.teamcode,
       a.accountofficercode,
       a.productcode,
       a.branchcode,
       a.currency,
       a.dateopened,
       a.maturitydate,
       a.status,
       a.isdormant,
       a.isjoint,
       a.accounttype,
       a.settlementacct,
       a.companycode,
       CASE a.teamcode WHEN NULL THEN x.miscode ELSE TO_CHAR (a.teamcode) END
          teamcodetemp,
       CASE a.accountofficercode
          WHEN NULL THEN TO_CHAR (x.aocode)
          ELSE TO_CHAR (a.accountofficercode)
       END
          accountofficercodetemp,
       a.contractrate,
       a.active,
       a.deleted,
       a.createdby,
       a.createdon,
       a.updatedby,
       a.updatedon,
       a.rowversion
  FROM mpr_customer_account a,
       (SELECT s.excoteamcode, s.excoaocode, s.companycode
          FROM mpr_setup s
         WHERE ROWNUM = 1) x;

SQL> create table my_demo (
  2  firstname varchar2(20),
  3  "FirstName" varchar2(20)
  4  )
  5  ;

Table created.

SQL> insert into my_demo
  2  values ('aaaa','bbbb')
  3  ;

1 row created.

SQL> select owner,
  2  	    table_name,
  3  	    column_name,
  4  	    data_type
  5  from dba_tab_cols
  6  where owner='ESTEVENS'
  7  and   table_name='MY_DEMO'
  8  ;

OWNER      TABLE_NAME COLUMN_NAME     DATA_TYPE
---------- ---------- --------------- ---------------
ESTEVENS   MY_DEMO    FIRSTNAME       VARCHAR2
ESTEVENS   MY_DEMO    FirstName       VARCHAR2

2 rows selected.

SQL> select owner,
  2  	    table_name,
  3  	    column_name,
  4  	    data_type
  5  from dba_tab_cols
  6  where owner='ESTEVENS'
  7  and   table_name='MY_DEMO'
  8  and column_name = 'firstname'
  9  ;

no rows selected

SQL> select owner,
  2  	    table_name,
  3  	    column_name,
  4  	    data_type
  5  from dba_tab_cols
  6  where owner='ESTEVENS'
  7  and   table_name='MY_DEMO'
  8  and column_name = 'FIRSTNAME'
  9  ;

OWNER      TABLE_NAME COLUMN_NAME     DATA_TYPE
---------- ---------- --------------- ---------------
ESTEVENS   MY_DEMO    FIRSTNAME       VARCHAR2

1 row selected.

SQL> select * from my_demo
  2  ;

FIRSTNAME            FirstName
-------------------- --------------------
aaaa                 bbbb

1 row selected.

SQL> select firstname,
  2  	    FirstName
  3  from my_demo
  4  ;

FIRSTNAME            FIRSTNAME
-------------------- --------------------
aaaa                 aaaa

1 row selected.

SQL> spo off