甚至不用replace_regexp，只用instr、substr和replace怎么样

with dt as (select 
'with result as (select column_a, column_b, count(*)  from (select column1, column2, column3 ..
select column1, count(distinct coalesce(column2, cast("zz" as nvarchar2(2)))) as value from ...
select count(*) from (select ....' as str from dual ),
 temp as ( 
select instr(str,'select'), instr(str,'from'), replace(substr(str,instr(str,'select')+length('select'),instr(str,'from')-instr(str,'select')-length('select')),',' ,' || ') fixed,
substr(str,0,instr(str,'select')+length('select')) astart ,
substr(str,instr(str,'select')+length('select'),instr(str,'from')-instr(str,'select')-length('select')) middle,
substr(str,instr(str,'from')) theend 
 from dt
 )
 select astart || middle || theend as  original, astart || fixed || theend as res
  from temp

字符集
下面是结果，稍后您所需要的就是编写一个适当的update语句。

original 

with result as (select  column_a, column_b, count(*)  from (select column1, column2, column3 ..
select column1, count(distinct coalesce(column2, cast("zz" as nvarchar2(2)))) as value from ...
select count(*) from (select ....

result

with result as (select  column_a ||  column_b ||  count(*)  from (select column1, column2, column3 ..
select column1, count(distinct coalesce(column2, cast("zz" as nvarchar2(2)))) as value from ...
select count(*) from (select ....

型