Leave only first 50 records in SQL database and delete the rest

问题

I have a table of scores, which is made of 2 fields: name and high score. Something like this:

----------------------- 
| name     | score    |
-----------------------
| John     | 2450     |
-----------------------
| Alice    | 2420     |
-----------------------
                         ... etc    

I need to delete all the rows till the top 50 scores.

Is it possible without creating another temporary table ?

回答1:

please try this

delete from scores_tbl Where
id not in
(select * from
(select id from scores_tbl order by score desc limit 50)
 as temp)

回答2:

Create an auto increment field

alter table scores add id int unique auto_increment not null;

This will automatically number your rows in the order of a select query without conditions or order-by

select * scores;
delete from scores where id > 50;

Finally, remove that field

alter table scores drop id;

回答3:

You need a unique field for this , so either alter the table before and after the delete.

Like : alter table scores add id int unique auto_increment not null;

delete from scores where id > 50;

alter table drop column id;

来源：https://stackoverflow.com/questions/21255578/leave-only-first-50-records-in-sql-database-and-delete-the-rest