To fetch the details of the teacher who joined after 1990, you can use the following SQL query, assuming you have a table called "Teachers" with a "JoinDate" column:
```sql
SELECT *
FROM Teachers
WHERE JoinDate greater than symbol '1990-12-31';
```
In this query:
- `Teachers` should be replaced with the actual name of your teacher table.
- `JoinDate` should be replaced with the actual name of the column that stores the join date of the teachers.
This query will retrieve all the details of teachers who joined after December 31, 1990.
#sql