Database

Not possible with the Database module.

The Dataform module allows you to select the entry owner when you add an entry. This way you can add entries on behalf of your students. Then if you set the activity Max entries to 0 and Separate participants to Yes, students cannot add entries on their own and when they enter the activity they can see only their designated entry. You can also import the students entries from csv by specifying the entry owner as the student username or idnumber.

hth

Solution 1: 

If you want a student can only see his/her own entries, simply set "Approval required=Yes", and don't add the tag "##approve##" into any template.

Then, students will ONLY see their own entries and teachers can see and edit all fields, include the 'Grade' field.

Solution 2: 

Set "Allow comments on entries=Yes", then, your teacher can post Grade into a student entries. only the student who enter that entry can see the posted comments.

Solution 3: 

You can also set "Ratings", you can set rate permission by teacher role only.

Above settings require students to add entry first.

Solution 4: 

If you don't need student to add entry at all, deliver your grades by "Grade".

Solution 5: 

If you don't need student to add entry at all, but want to deliver your grade in a sort of form, set up an 'offline assignment', and upload your Word form files into each student's 'Feedback"(you can do this by a zip file quickly).

Solution 6: 

If you don't need student to add entry at all, but want to deliver your grade in a sort of form, set up an 'offline assignment', and attach a "Rubric".

HTH