[Feature] Support Join and sub-queries for the SQL parser

[suntong]

Please support Join and sub-queries for the SQL parser.

It's a test of expressiveness and limitation of participle.

Thanks

[alecthomas]

The _examples folder is just that, examples. If they are to be extended, contributions are welcome. That said there are other examples, including the minio S3 select parser.

[suntong]

there are other examples, including the minio S3 select parser.

I took a look and neither seems to be able to support Join and sub-queries for SQL select.

I'm asking because I don't know if participle is capable of supporting them, as that's a test of expressiveness and limitation of participle.

[alecthomas]

Participle is a general purpose parser, there's no limitation that would effect this.