Doris always delays the execution of expressions as possible as it can, so as the expansion of constant expression. Given below SQL:
```sql
select i from (select 'abc' as i, sum(birth) as j from subquerytest2) as tmp
```
The aggregation would be eliminated, since its output is not required by the outer block, but the expasion for constant expression would be done in the final result expr, and since aggreagete output has been eliminate, the expasion would actually do nothing, and finally cause a empty results.
To fix this, we materialize the results expr in the inner block for such SQL, it may affect performance, but better than let system produce a mistaken result.
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