迁移自引用外键问题

Question

我正在为Lumen项目使用Laravel迁移，其中我有树类型表：| id | name | parent_id。但是我需要使用外键。我只是感兴趣，下面的解决方案是否是一个好的解决方案？还是有更好的解决方案？

MP <- data.table(
  M = c("m1","m1","m1","m2","m2", "m1"),
  P = c("p1","p2","p4","p1","p3", "p1")
)

MK <- data.table(
  M = c("m1","m1","m2"),
  K = c("k1","k2","k1")
)

FINAL EXPECTED RESULT
M   P   K
m1  p1  k1
m1  p1  k2
m1  p2  k1
m1  p2  k2
m1  p4  k1
m1  p4  k2
m2  p1  k1
m2  p3  k1