Auto_increment value needs to be set as S1
Autoincrement values can only be numeric (integer and floats types if I remember correctly).

If you want to store S1, ...., S1000, just store an integer, and return the extra S on select or on client side:

create table tbl(ID bigint not null primary key auto_increment,name varchar(100)) auto_increment=1;

insert into tbl (name) values ('a');
...

select concat('S', id) as id, name from tbl;
+----+------+
| id | name |
+----+------+
| S1 | a    |
| S2 | a    |
| S3 | a    |
| S4 | a    |
...