Support multi-column-expr when doing a SELECT

[Adriel-M]

Supports AlecKazakova/sql-psi#411

[Adriel-M]

A change to allow me to understand how multi_column_expr works.

In the future I want to support:

DELETE FROM table
WHERE (colA, colB) IN ((?, ?), (?, ?))

which will used to deleting by a composite primary key.

But this is not supported in sql-psi.

[Adriel-M]

Can I assume this will not return null?

From https://github.com/AlecStrong/sql-psi/blob/master/core/src/main/kotlin/com/alecstrong/sql/psi/core/sql.bnf#L237

these two expressions are not optional.

[hfhbd]

Yes

[Adriel-M]

The types look right here

[hfhbd]

Very nice, thank you!

[hfhbd]

@Adriel-M Please run './gradlew :spotlessApply' to fix the code violations.

[Adriel-M]

@hfhbd linted

[Adriel-M]

@hfhbd btw, the linked issue wouldn't be resolved.

IN isn't part of of multi_column_expr. It would probably need a new expr that looks something like:

multi_column_in_expr ::= multi_column_expression IN LP multi_column_expression (COMMA multi_column_expression) * RP {
  pin = 2
}

[hfhbd]

@Adriel-M yeah you are right, will reopen it.