使用SQL查找有向图中的周期

从这些信息中，我们获取开始的路径列表并在同一个节点结束。

从这个最终边的列表中，我们根据前两步的计算重新构建所有循环的路径。

我发布了 TSQL 在我的博客上。

There are already a couple of questions on finding cycles, but I did not find a solution in SQL (MSSQL preferred).

The tables would be Node (NodeID INT) and Edge (EdgeID INT, NodeID1 INT, NodeID2 INT)

What would be a well-performing solution to find cycles in a directed graph?

The solution turned out quite simple and straightforward, but a bit longer:

First the list of all paths through the graph is generated, such that no path contains the same edge more than once.

From this information, we take the list of paths that start and end in the same node.

From this list of "final" edges we reconstruct all paths with cycles based on the calculation of the previous two steps.

I posted the complete solution in TSQL on my blog.