我正在尝试创建一个接受字符串作为参数的函数，如下所示
this is a sample string and i need to use uppercase letter for every third word in this string
以及如何获得如下输出
position;word
-------------
3 ;"a"
6 ;"and"
9 ;"to"
12 ;"letter"
15 ;"third"
18 ;"this"
我知道如何创建一个函数，但我找不到找到我想要的输出的方法
create or replace function fn_every_third(str text) returns table(pos bigint,wrd text) as
$$
--code to get the output
$$
language sql
create or replace function fn_every_third(str text) returns table(pos bigint,wrd text) as
$$
with cte as(
select * from(
select row_number() over() rn,word from(
select unnest(regexp_split_to_array(str,' ')) word)t)q
)
select rn ,word from cte
where rn in (select generate_series(3,(select max(rn) from cte),3))
order by rn
$$
language sql
利用：
select *
from fn_every_third('this is a sample string and i need to use uppercase letter for every third word in this string')
参考：