Source records of parent SQL query records

Question

We have subfolders with parent-child relationships. We use MySQL MyISAM DB. Data is stored in the database as follows.

Each time a child folder is created in a nested structure, the previous parent identifier is added. I want to get the RootFolderID from a folder that is added to the hierarchy, as shown below.

FoldID  ParentID |RootFolderID
-----------------|-------------------
1         0      | 0
2         1      | 1
3         2      | 1
4         3      | 1
5         4      | 1

Please let me know how to get the root folderID and fill it in the RootFolderID column after creating the folder every time.

Thank.

Answer 1

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