for example: ```sql with a as (with a as (select * from t) select * from a) select * from a; with a as (select * from t1), b as (with a as (select * from a) select * from a) select * from b; ```
for example: ```sql with a as (with a as (select * from t) select * from a) select * from a; with a as (select * from t1), b as (with a as (select * from a) select * from a) select * from b; ```