135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
|
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
|
+
-
-
-
+
+
+
-
-
+
+
+
+
|
as
(
select 'A', null union all
select 'F', null union all
select 'B', 'A' union all
select 'C', 'B' union all
select 'E', 'F' union all
select 'H', 'E' union all
select 'G', 'E' union all
select 'D', 'C'
),
Hierarchy( node, parent, level, path, isHead, isTail )
as
(
select DataSet.node,
'NULL', -- DataSet.parent,
1 as level,
select DataSet.node as node,
'NULL' as parent, -- DataSet.parent,
0 as level,
' → ' || DataSet.node as path,
DataSet.parent IS NULL,
NOT EXISTS (SELECT 1 FROM DataSet d WHERE d.parent=DataSet.node)
from DataSet
where DataSet.parent is null
union all
select DataSet.node,
DataSet.parent,
select DataSet.node as node,
DataSet.parent as parent,
Hierarchy.level + 1 as level,
Hierarchy.path || ' → ' || DataSet.node as path,
DataSet.parent IS NULL,
NOT EXISTS (SELECT 1 FROM DataSet d WHERE d.parent=DataSet.node)
from Hierarchy
join DataSet
on DataSet.parent = Hierarchy.node
ORDER BY parent, node
)
select *
from Hierarchy
-- where level>1
order by path;
</pre></nowiki>
|