Pilih mysql rekursif?

CREATE DEFINER = 'root'@'localhost'
PROCEDURE test.GetHierarchyUsers(IN StartKey INT)
BEGIN
  -- prepare a hierarchy level variable 
  SET @hierlevel := 00000;

  -- prepare a variable for total rows so we know when no more rows found
  SET @lastRowCount := 0;

  -- pre-drop temp table
  DROP TABLE IF EXISTS MyHierarchy;

  -- now, create it as the first level you want... 
  -- ie: a specific top level of all "no parent" entries
  -- or parameterize the function and ask for a specific "ID".
  -- add extra column as flag for next set of ID's to load into this.
  CREATE TABLE MyHierarchy AS
  SELECT U.ID
       , U.Parent
       , U.`name`
       , 00 AS IDHierLevel
       , 00 AS AlreadyProcessed
  FROM
    Users U
  WHERE
    U.ID = StartKey;

  -- how many rows are we starting with at this tier level
  -- START the cycle, only IF we found rows...
  SET @lastRowCount := FOUND_ROWS();

  -- we need to have a "key" for updates to be applied against, 
  -- otherwise our UPDATE statement will nag about an unsafe update command
  CREATE INDEX MyHier_Idx1 ON MyHierarchy (IDHierLevel);


  -- NOW, keep cycling through until we get no more records
  WHILE @lastRowCount > 0
  DO

    UPDATE MyHierarchy
    SET
      AlreadyProcessed = 1
    WHERE
      IDHierLevel = @hierLevel;

    -- NOW, load in all entries found from full-set NOT already processed
    INSERT INTO MyHierarchy
    SELECT DISTINCT U.ID
                  , U.Parent
                  , U.`name`
                  , @hierLevel + 1 AS IDHierLevel
                  , 0 AS AlreadyProcessed
    FROM
      MyHierarchy mh
    JOIN Users U
    ON mh.Parent = U.ID
    WHERE
      mh.IDHierLevel = @hierLevel;

    -- preserve latest count of records accounted for from above query
    -- now, how many acrual rows DID we insert from the select query
    SET @lastRowCount := ROW_COUNT();


    -- only mark the LOWER level we just joined against as processed,
    -- and NOT the new records we just inserted
    UPDATE MyHierarchy
    SET
      AlreadyProcessed = 1
    WHERE
      IDHierLevel = @hierLevel;

    -- now, update the hierarchy level
    SET @hierLevel := @hierLevel + 1;

  END WHILE;


  -- return the final set now
  SELECT *
  FROM
    MyHierarchy;

-- and we can clean-up after the query of data has been selected / returned.
--    drop table if exists MyHierarchy;


END

Ini mungkin tampak rumit, tetapi untuk menggunakan ini, lakukan

call GetHierarchyUsers( 5 );

(atau ID kunci apa pun yang Anda ingin temukan UP hierarki pohonnya).

Premisnya adalah memulai dengan satu KUNCI yang sedang Anda kerjakan. Kemudian, gunakan itu sebagai dasar untuk bergabung ke tabel pengguna LAGI, tetapi berdasarkan ID INDUK entri pertama. Setelah ditemukan, perbarui tabel temp agar tidak mencoba dan bergabung untuk kunci itu lagi pada siklus berikutnya. Kemudian teruskan sampai tidak ada lagi kunci ID "induk" yang dapat ditemukan.

Ini akan mengembalikan seluruh hierarki catatan ke induk tidak peduli seberapa dalam sarangnya. Namun, jika Anda hanya menginginkan induk FINAL, Anda dapat menggunakan variabel @hierlevel untuk mengembalikan hanya yang terbaru dalam file yang ditambahkan, atau ORDER BY dan LIMIT 1