Does not support the AS keyword

I didn’t find any field in Statement indicating whether to use the AS field. I think it’s necessary to mark it.

Start by locating the Statement type mentioned in the issue and tracing how the relevant SQL statement is parsed. Determine where AS usage would be represented, then verify that the reported syntax is accepted and its alias information is preserved. The issue provides no file or test path, so repository-wide search will be needed.

索引モデルが issue の本文から書いたものです。