In the following select :
select t.x from t
t.x is a select element and t is it's origin
Here q.z1 is a SelectElement who's origin is t
select q.z1
from
(select t.x as z1 from t) q
strictly for logging purposes, i.
strictly for logging purposes, i.e. to display a more explicit AST
Update, Insert, and Delete statements are always at the root of an AST, so they are never aliased, but then can have sub queries, ex.
Update, Insert, and Delete statements are always at the root of an AST, so they are never aliased, but then can have sub queries, ex.: update ... where x in (subquery). Name clashes are impossible since SelectElements of query are always aliased.
visitor's args are : -the visited node, -it's parent -it's depth
visitor's args are : -the visited node, -it's parent -it's depth
SelectElement are elements of a select list, for example they are a,b, and c in :
select a,b,c from T
they are either ValueSelectElement for composite expressions, i.e. select (x / 2) * y as Z from .... TupleSelectElement for group by or compute elements (TODO: document group by/compute) FieldSelectElement for table columns (that map to fields)
ExportSelectElement for a select element that refers to a SelectElement of an inner or outer query.
SelectElementReference are nodes in any clause other than select (where, having, composite expression, order by, etc) that refer to a SelectElement