How do I drop duplicate data from a table?

Assume there is a student table: students(id char(5),name char(20)); To drop duplicate data from this table:

1. Use select to move the duplicate id to a temporary table, 'temptable':

dmSQL> select id

    2>   from student

    3>   group by id having count(*)1

    4>   into temptable;

2. Then drop all the duplicate id data

dmSQL> delete from student

    2>   where id in (

    3>     select id from temptable

    4>   );

Caution:

1. If there are two records including id=3008,these two records will be deleted.
2. You can build an index in the id and name columns, which will speed up execution time.