I have 2 table

Table 1: EnrollmentTransaction

EnrollmentId | TransactionId
5            | 1
5            | 2
6            | 3
7            | 2
8            | 3
8            | 2
8            | 1

Table 2: EnrollmentDetail (TransactionId column added newly with default value 1 since it’s not null column)

EnrollmentId | ParameterId| TransactionId 
5            | 1          | 1
6            | 8          | 1
7            | 9          | 1
7            | 6          | 1
8            | 8          | 1

By referring to Table 1, I would like to insert if there is no entry or update if there is an entry based on EnrollmentId.

For example,
Scenario 1: EnrollmentId 5 has 2 entries in table 1 whereas, table 2 has only 1 entry and I must insert one more row with values 5, 1, 2 in table 2.

Sceanrio 2: EnrollmentId 6 has only 1 entry in table 1 and I need to update with value 6, 8 , 3 in table 2.

Is there any possibility to write a single query to achieve this?

Note: Oracle 19 is the database.