SQL Query

Assume that a sample table contains parent and child relationships. The table has three fields: ID$,$ Parent ID$,$ and Data. The ID field specifies the identifier for a tuple. Null values are not allowed. The Parent ID field points to ID in the same table. The Data field contains some information about the association.

Considering the above, answer the following questions:

How will you display hierarchy in this table using minimum query?

What kind of schema will you use to represent a tree$-$like data structure for this hierarchy using relational database design?

Please provide diagrams.