qustion about INTERSECT in SqlBase.g4

[boson234]

why not merge these two into one in SqlBase.g4?

just like
left=queryTerm operator=(INTERSECT | UNION | EXCEPT) setQuantifier? right=queryTerm #setOperation

[martint]

INTERSECT has different precedence than EXCEPT and UNION. In Antlr, when there are left-recursive rules, the order of the alternatives determines the precedence.