Support MySQL ROWS syntax for VALUES

[aljazerzen]

MySQL does not support following query:

VALUES (1)

... but supports ...

VALUES ROW(1)

https://dev.mysql.com/doc/refman/8.0/en/values.html

Note that is does support:

INSERT INTO my_table VALUES (1)

Quality of my code reflects banality of this detail.

[alamb]

Thank you @aljazerzen

The code and tests look good except for the within_insert special case

[alamb]

How important is it to reject the ROWS keyword during inserts? I see that mySQL is not consistent in that ROW is not allowed in INSERT statements https://dev.mysql.com/doc/refman/8.0/en/insert.html

However, I also don't see any (negative) tests for this case in this PR, though maybe I have missed them

My preference is to remove the special case handling for in select and make the parser permissive and support an optional ROW whenever a VALUES list is specified.

Downstream crates that care can detect explicit_row and error if they don't want to allow that syntax.

We tried to make the philosophy of "parse all the things" clearer recently in the introduction here https://github.com/sqlparser-rs/sqlparser-rs#extensible-sql-lexer-and-parser-for-rust

[alamb]

BTW I found

Quality of my code reflects banality of this detail.

😆

[aljazerzen]

Yeah that makes sense - there is no need to inforce explict row. And it simplifies the code a lot!

[coveralls]

Pull Request Test Coverage Report for Build 3590726471

• 39 of 39 (100.0%) changed or added relevant lines in 5 files are covered.
• 907 unchanged lines in 6 files lost coverage.
• Overall coverage decreased (-0.01%) to 86.36%

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Files with Coverage Reduction	New Missed Lines	%
src/tokenizer.rs	1	90.28%
tests/sqlparser_postgres.rs	24	97.32%
src/ast/query.rs	27	85.32%
tests/sqlparser_common.rs	37	97.25%
src/ast/mod.rs	295	77.39%
src/parser.rs	523	83.56%

Totals
Change from base Build 3577821724:	-0.01%
Covered Lines:	12194
Relevant Lines:	14120

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💛 - Coveralls

[alamb]

Looks good -- thank you @aljazerzen