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How to use recursive CTE with insert select?
I’m trying to use recursive CTE with INSERT SELECT to create some test Data. For simplicity follows below a single column table to be populated: The above generates a syntax error. Note that if the insert line is removed then the 10 rows will appear as expected with values 1 to 10 from the SELECT statement.
How to select using with recursive clause?
Can anybody give very clear explanation demonstrating such query semantics and execution process, better based on typical samples like factorial calculation or full tree expansion from (id,parent_id,name) table? And what are the basic guidlines and typical mistakes that one should know to make good with recursive queries?
When does the recursive SELECT query in MySQL work?
Note This only works when every record’s “id” (col1 in the question) has a value GREATER THAN that record’s “parent id” (col3 in the question). This is often the case, because normally the parent will need to be created first.
How to create a recursive query in Oracle?
The Oracle syntax uses a CONNECT BY PRIOR clause to build the tree and a START WITH clause that tells the database where to start walking the tree. It will look like this: SELECT child, parent, level FROM family_tree CONNECT BY START WITH
Which is an anchor member in a recursive CTE?
An initial query that returns the base result set of the CTE. The initial query is called an anchor member. A recursive query that references the common table expression, therefore, it is called the recursive member. The recursive member is union-ed with the anchor member using the UNION ALL operator.
What is a recursive common table expression ( CTE )?
A recursive common table expression (CTE) is a CTE that references itself. By doing so, the CTE repeatedly executes, returns subsets of data, until it returns the complete result set.
Do you need a recursive CTE in PostgreSQL?
You don’t need a recursive CTE, you can use nextval () in the result from the unnest () directly and then use lag () to get the value from the previous row. To deal with existing rows, I would do this using a join between the result of the unnest () and the path table, detecting new and existing rows.