MySQL根据Unix / Epoch时间的最后两位数字删除条目

Question

I have a table with three columns:

  `id` int(11) NOT NULL auto_increment    
  `tm` int NOT NULL    
  `ip` varchar(16) NOT NULL DEFAULT '0.0.0.0'

I want to run a query that will check if the same IP was logged within a minute and then delete all but one of those entries.

For example I have the two rows below.

id=1 tm=1361886629 ip=192.168.0.1
id=2 tm=1361886630 ip=192.168.0.1

I would only like to keep one in the database.

I have read lots of other remove duplicate/partial duplicate entry questions but I'm looking for a way to compare the last two digits of the Unix/epoch time and delete all but one based on that plus the IP.

Any help is much appreciated.

Answer 1

you can use CAST in mysql to remove the last 2 digits

SELECT CAST( tm AS CHAR( 8 ) )

this will select only the first 8 digits from the timestamp and allow you to find duplicates

if you only want to know what the last 2 digits are

SELECT RIGHT(CAST( tm AS CHAR( 10 ) ), 2)

this will select the last two digits only from each timestamp