AWS Athena：如何转义保留字列名并转换为 integer

Question

I have a column named 'timestamp' which is a reserved word. I need to select the column then cast it as an integer to perform the query below. I can successfully perform a simple select of the column data. It is only when I try to cast the value as an integer that the error is returned.

I have tried to escape the word using backticks and double quotes as suggested in the AWS Docs without success.

*The query works with another table that does not use a reserved word for the column name. This is what I have attempted:

Query with reserved word un-escaped:

SELECT timestamp
FROM my_table
WHERE from_unixtime(cast(timestamp as integer)) >= date_add('day', -7, now())

Error:

INVALID_CAST_ARGUMENT: Cannot cast '' to INT

Query with backticks:

SELECT `timestamp`
FROM my_table
WHERE from_unixtime(cast(`timestamp` as integer)) >= date_add('day', -7, now())

Error:

Queries of this type are not supported

Query with double quotes:

SELECT "timestamp"
FROM my_table
WHERE from_unixtime(cast("timestamp" as integer)) >= date_add('day', -7, now())

Error:

INVALID_CAST_ARGUMENT: Cannot cast '' to INT

Thanks!

Answer 1

The problem is not your escaping logic, but that your dataset contains empty strings in the timestamp column which can not be casted. You can avoid that, by filtering out the empty string records.

SELECT "timestamp"
FROM (SELECT "timestamp" from my_table where "timestamp" != '')
WHERE from_unixtime(cast("timestamp" as integer)) >= date_add('day', -7, now())

Answer 2

Instead of cast you can use try_cast which returns null in case of unsuccessful cast (empty string can't be turned into integer ), which will result in the where condition evaluated to false:

with dataset(col) as (
    values (''),
    ('1659648600')
)

select *
from dataset
where from_unixtime(try_cast(col as integer)) >= date '2022-08-03';

Output:

col
1659648600