delete all from table

Question

what's faster?

DELETE FROM table_name;

or

DELETE FROM table_name where 1=1;

why?

does truncate table work in access?

Solution 1

You can use the below query to remove all the rows from the table, also you should keep it in mind that it will reset the Identity too.

TRUNCATE TABLE table_name

Solution 2

This should be faster:

DELETE * FROM table_name;

because RDBMS don't have to look where is what.

You should be fine with truncate though:

truncate table table_name

Solution 3

This is deletes the table table_name.

Replace it with the name of the table, which shall be deleted.

DELETE FROM table_name;

Solution 4

There is a mySQL bug report from 2004 that still seems to have some validity. It seems that in 4.x, this was fastest:

DROP table_name
CREATE TABLE table_name

TRUNCATE table_name was DELETE FROM internally back then, providing no performance gain.

This seems to have changed, but only in 5.0.3 and younger. From the bug report:

[11 Jan 2005 16:10] Marko Mäkelä

I've now implemented fast TRUNCATE TABLE, which will hopefully be included in MySQL 5.0.3.

Solution 5

TRUNCATE TABLE table_name

Is a DDL(Data Definition Language), you can delete all data and clean identity. If you want to use this, you need DDL privileges in table.

DDL statements example: CREATE, ALTER, DROP, TRUNCATE, etc.

DELETE FROM table_name / DELETE FROM table_name WHERE 1=1 (is the same)

Is a DML(Data Manipulation Language), you can delete all data. DML statements example: SELECT, UPDATE, etc.

It is important to know this because if an application is running on a server, when we run a DML there will be no problem. But sometimes when using DDL we will have to restart the application service. I had that experience in postgresql.

Regards.

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Comments

[user2476101]

No, would have helped if you mentioned Access in your original question. In which case, DELETE FROM table_name will do the job quickest as answered below.

[user2476101]

No, it's not supported in Access.

[BoltClock]

Bear in mind that TRUNCATE will reset all AUTO_INCREMENT counts on MySQL tables (not sure if MS Access has such a thing).

[user2476101]

Access does not maintain a transaction log, which is why there's no need for the TRUNCATE statement, and why the DELETE FROM table_name will do the job nicely.

[David-W-Fenton]

Jet treats DELETE * FROM Table as a truncate, instead of deleting the records one by one. I don't think it resets the Autonumber seed value, though. That has to be done in code or with a compact (not even sure it will reset with a compact in recent iterations of Jet/ACE).

[Donald Byrd]

It should be noted that DELETE and TRUNCATE are not the same thing. TRUNCATE has side effects and typically requires more permissions to execute.

[Ben]

I can confirm that if all records are deleted from an Access table, a Compact will reset the Autonumber seed value in Access 2016.

[Spinstaz]

This doesn't delete the table, it deletes all the rows from the tables and allows you to then continue to use the table unaffected. This is perfect for me, thanks.