SelectWithUnionQuery (children 1) ExpressionList (children 1) SelectQuery (children 2) ExpressionList (children 1) Function if (alias res) (children 1) ExpressionList (children 3) Identifier constant_true Identifier then_non_constant_nullable Identifier else_non_constant TablesInSelectQuery (children 1) TablesInSelectQueryElement (children 1) TableExpression (children 1) TableIdentifier nullable_00431