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How can I select rows from a hierarchical query?
If you have an hierarchical query that produces the whole tree under the root node, that also has a level column computed, you can wrap it in a derived table or cte and use the window aggregate: You could put the hierarchical query in a subquery and user an analytic function and windowing to figure out the first match.
How to include top-level parent in Oracle hierarchical query?
Regards, Rob. You need to do the hierarchy the other way around, from the root to the leaves.
Can a non-uniform hierarchy be 3 levels deep?
So, I am wanting to generate a non-uniform hierarchy that follows these rules: All branches will be 3 levels deep. Uniformity in depth is ok at this point. There can be overlap in names of child nodes on any given level (i.e. names of child nodes do not need to be unique across all nodes on the same level).
Is there overlap in names of child nodes?
There can be overlap in names of child nodes on any given level (i.e. names of child nodes do not need to be unique across all nodes on the same level). The term “random” is defined here as being pseudo-random, not uniquely random.
How does a hierarchical query work in Oracle?
STARTWITHspecifies the root row(s) of the hierarchy. CONNECTBYspecifies the relationship between parent rows and child rows of the hierarchy. The NOCYCLEparameter instructs Oracle Database to return rows from a query even if a CONNECTBYLOOPexists in the data.
How does Oracle eliminate rows from a hierarchy?
If the query contains a WHEREclause without a join, then Oracle eliminates all rows from the hierarchy that do not satisfy the condition of the WHEREclause. Oracle evaluates this condition for each row individually, rather than removing all the children of a row that does not satisfy the condition.
How does Oracle select children in a hierarchy?
Oracle always selects children by evaluating the CONNECTBYcondition with respect to a current parent row. If the query contains a WHEREclause without a join, then Oracle eliminates all rows from the hierarchy that do not satisfy the condition of the WHEREclause.