usesuper::{Project, SqlExpr, SqlFrom};/// The AST for the SQL subscription language
pubenumSqlAst{
Select(SqlSelect),/// UNION ALL
Union(Box<SqlAst>,Box<SqlAst>),/// EXCEPT ALL
Minus(Box<SqlAst>,Box<SqlAst>),}/// A SELECT statement in the SQL subscription language
pubstructSqlSelect{pubproject: Project,
pubfrom:SqlFrom<SqlAst>,
pubfilter:Option<SqlExpr>,
}