How to append to list?

I have a table 's' containing strings:

1. 'STRING_A'
2. 'STRING_B'
3. 'STRING_C'
4. 'STRING_D'
5. 'STRING_E'

and a list of strings that i want to insert into 's':

1. 'STRING_C'
2. 'STRING_D'
3. 'STRING_E'
4. 'STRING_B'
5. 'STRING_A'

I want to insert only those items that do not overlap with records in the table 's'.

Result table 's':

1. 'STRING_A'
2. 'STRING_B'
3. 'STRING_C'
4. 'STRING_D'
5. 'STRING_E'
6. 'STRING_B'
7. 'STRING_A'

Can it be done without leaving sql?