将mySQL数据库的日志文件日期时间格式从12小时时钟批量转换为24小时时钟

Question

I am creating a web app to analyze data from a client's custom database. I am having difficulty finding a way how to convert the client's log file entries from 12 hour clock to 24 hour clock. The Database that I am setting this up with cannot read 12 hour time format, so is displaying the time wrong.

Log files I am using look like this:

Site_Name,number_of_clicks,DD/MM/YYYY_2:00PM,Interaction_Type

I need to convert the log files to look like this:

Site_Name,number_of_clicks,DD/MM/YYYY_14:00,Interaction_Type

There are tens of thousands of enteries per log file, so there is no way this can be done per entry. I need to figure out a way to bulk convert the entries to 24-hour clock for each of the log files.

Any help would be greatly appreciated!

Thanks!

Aaron

Answer 1

If you want to do that on db side and you use MySql you can read it with STR_TO_DATE() and either use it as a datetime value

INSERT INTO log (`Site_Name`, `number_of_clicks`, `date`, `Interaction_Type`)
SELECT 'site1', 10, STR_TO_DATE('10/05/2013_2:00PM', '%d/%m/%Y_%l:%i%p'), 1;

or

UPDATE log
   SET date = STR_TO_DATE(str_date, '%d/%m/%Y_%l:%i%p');

assuming that date column is of type datetime, and str_date column contains string values in 12h format.

or if for some reason you store it as VARCHAR and really need to format it as DD/MM/YYYY_14:00 then you can use DATE_FORMAT()

DATE_FORMAT(STR_TO_DATE('10/05/2013_2:00PM', '%d/%m/%Y_%l:%i%p'), '%d/%m/%Y_%k:%i')

which will produce

|          NEWDATE |
--------------------
| 10/05/2013_14:00 |

To update in-place

UPDATE log
   SET str_date = DATE_FORMAT(STR_TO_DATE(str_date, '%d/%m/%Y_%l:%i%p'), '%d/%m/%Y_%k:%i');

Here is SQLFiddle demo.

Answer 2

Why don't you write a simple app that will search through all log entries and update whenever it finds date in PM format. You basically need to write a piece of code that will add 12 hrs if there is PM in the time.

Here is a rough code in C#... not fully tested but you can build on this…

protected string ConvertToPM(string logEntry)

{
    string result = string.Empty;

//DD/MM/YYYY_2:00PM
if (logEntry.Contains("PM"))
{
   string temp = logEntry.Substring(logEntry.IndexOf("_"), logEntry.IndexOf(":") - logEntry.IndexOf("_"));

    result = logEntry.Replace(temp, (Convert.ToInt32(temp) + 12).ToString());
}

return result;
}

Just add a piece of code that will a) read log file line by line b) extract date part c) use function similar to the one above to alter the data…