Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Welcome To Ask or Share your Answers For Others

Categories

0 votes
785 views
in Technique[技术] by (71.8m points)

mysql - Delete first X lines of a database

is there an SQL command to delete the first X lines of a database table?

I have a database table containing some information but no id or auto-incrementing value and a program that processes the first X lines of this table. Afterwards these X lines need to be deleted. So the standard query is:

DELETE FROM table WHERE something = value;

So, is there a way to build a query like:

DELETE FROM table WHERE rownumber <= X;

I have tried this command, but nothing happens to the database.. Do you have any clue?

See Question&Answers more detail:os

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome To Ask or Share your Answers For Others

1 Reply

0 votes
by (71.8m points)

Use LIMIT on your delete:

DELETE FROM table WHERE condition LIMIT 10

Or, if you don't want the condition

DELETE FROM table LIMIT 10

Remember that the order in which rows will be deleted is undefined - it depends on your DBMS configuration and table indices. You should include an ORDER BY so that the deletion is done in a defined order, e.g. ORDER BY id ASC to delete the lowest IDs first.

See the MySQL documentation for DELETE for more details.


与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
OGeek|极客中国-欢迎来到极客的世界,一个免费开放的程序员编程交流平台!开放,进步,分享!让技术改变生活,让极客改变未来! Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Click Here to Ask a Question

...