Question

Consider the following three tables where keys are underlined: Graphs(graphid, graphname), Nodes(nodeid, nodename, nodeweight, graphid), Edges(parentid, childid, edgeweight, graphid), formulate a SQL statement for each query in the following.

2. Assume each node has a different weight, return the nodeids of the top three nodes that have the highest weight for the graph with graphid = 1234.

Answer 1

SQL Query return the node ids of the top three nodes that have the highest weight for the graph with graphid = 1234.

SELECT nodeid FROM
    (
    SELECT *
     FROM Nodes
    where graphid = 1234 
    ORDER BY nodeweight desc
    )
WHERE rownum <= 3
ORDER BY nodeweight ;

Explanation

First we get all the information of the Nodes where graphid=1234 then sort them according to node weight in descending order .

Now from the above output we extract node ids of first 3 rows by using rownum .

Hence we get Output as Top Three ids as the final result

So this is how you can get the needed data in SQL

Thank You

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