How to disable and enable depended constraints

select
--'truncate table '|| TABLE_NAME || ';'
'alter table ' || TABLE_NAME || ' enable constraint ' || CONSTRAINT_NAME || ';'
from ALL_CONSTRAINTS
where CONSTRAINT_TYPE = 'R'
  and STATUS <> 'ENABLED'
  --and R_CONSTRAINT_NAME = 'C_MEDHISTCONS_PK'
order by TABLE_NAME

select 'alter table ' || TABLE_NAME || ' disable constraint ' || CONSTRAINT_NAME || ';'
from ALL_CONSTRAINTS
where CONSTRAINT_TYPE = 'R'
  and R_CONSTRAINT_NAME = 'C_DCSPECS_PK'  

How to create indexes by foreign key

select 'create index I_' || substr(C.CONSTRAINT_NAME, 3) || ' on ' || C.TABLE_NAME || '(' || 
  (select rtrim(xmlagg(xmlelement(e, CC.COLUMN_NAME,',').extract('//text()') order by CC.COLUMN_NAME).GetClobVal(),',')
   from ALL_CONS_COLUMNS CC
   where CC.OWNER = C.OWNER
     and CC.TABLE_NAME = C.TABLE_NAME
     and CC.CONSTRAINT_NAME = C.CONSTRAINT_NAME) || ');'
from (
  select distinct C.OWNER, C.TABLE_NAME, C.CONSTRAINT_NAME
  from
    ALL_CONSTRAINTS C,
    ALL_CONS_COLUMNS CC
  where C.CONSTRAINT_TYPE = 'R'
    and C.OWNER = 'PARUS'
    and CC.OWNER = C.OWNER
    and CC.TABLE_NAME = C.TABLE_NAME
    and CC.CONSTRAINT_NAME = C.CONSTRAINT_NAME
    and not CC.COLUMN_NAME in ('COMPANY', 'VERSION')
    and CC.CONSTRAINT_NAME like 'C\_%' escape '\'
    and not exists (
      select *
      from ALL_IND_COLUMNS IC
      where IC.TABLE_OWNER = C.OWNER
        and IC.TABLE_NAME  = CC.TABLE_NAME
        and IC.COLUMN_NAME = CC.COLUMN_NAME)) C

How to reverse string

select listagg(C) within group(order by RN desc) rvs
from (
  select substr(T.COL, rownum, 1) C, rownum RN
  from (select 'Привет' COL from DUAL) T
  connect by level <= length(T.COL))