First of all im a starter,iam using eclipse.
I want to add current date and time of login in to db and search a day and find out the time between login and logout.
°What is the data type for the date colum in mysql ?
°Is it necessary separate column for date and time ?
°which one i want to import, java.util.date or java.sql.date ?
°In Java code simple date format or calender is better ?
Advanced thanks.....
You might want to read this:
Should I use field 'datetime' or 'timestamp'?
For example, if you have mysql populate the log record's date/time (using "DEFAULT CURRENT_TIMESTAMP" in your field definition), you will want to use timestamp. For certain situations where you fill a date value from your application, you may wish to use datetime. Be careful with timezones.
Here are the date functions in mysql:
https://dev.mysql.com/doc/refman/5.7/en/date-and-time-functions.html
DATEDIFF(), for example, will calculate the number of days between two datetimes. If you use unix timestamps, you can use standard arithmetic between the values to find the number of seconds between them, and then calculate minutes, hours, days, etc. by dividing appropriately.
This answer is focused on how to handle the dates in mysql. Not enough info to provide guidance on java.
Related
Let's say I have a date dimension and from my business requirements I know that the most granular I would need to go is to examine the specific day of the month that an event occurred.
The data I am given provides me with the exact time that an event occurred (YYYY-MM-DD HH:MM:SS). I have two opitons:
Before loading the data into the date dimension, slice the HH:MM:SS from the date.
Create the time attributes in my date dimension and insert the full date time.
The way I see it, I should go with the option 1. This would remove redundant data and save some space. However, if I go with option 2, should the business requirements ever change or if my manager suddenly wants to be more granular I wouldn't need to modify my original design. Which option is more commonly used? Are there more options that I did not consider?
Update - follow up question
I receive new data every month. If I used a pre built date dimension with all the dates would I then need to run my script every month to populate the table with new dates of that month or would I have a continuous process where by every day insert into the table one row, which would be that date?
I would agree with you and avoid option 2. A standard date dimension table is at the individual date level. If you did need to analyse by time of day, you could create an additional time of day dimension at the level of a second in a single day, and link to that from your fact table.
Your date dimension should be created by script automatically, rather than from the dates that events occurred. This allows you to analyse across a range of events from other facts, and on dates where no events occur, using a standard, prebuilt dimension.
I would also include the full date/time stamp as a column in the fact table, along with the 'DateKey' to the dimension table. This would allow you some visibility/analysis of the timestamp, you would not lose the data, and would still allow you to analyse by the date dimension.
Update - follow up question
Your pre-built date dimension (the standard way of doing it) would usually contain some dates in the future. There's no reason not to, for example, include another 5 years of dates in the table. But if you'd like it to gradually grow over time, you could have a script that is run once a day, once a month, or once a year to add new dates. Its totally up to you! There are many example scripts for building date dimensions- just google date dimension script. They exist for the language of your choice, e.g. SQL, C#, Power Query, etc.
I have a decimal date field (TDDATR) that is in the YYYYMMDD format.
I would like to create a field that is TDDATR + 30 days but I am unable to.
Using 'Define Results Field' I have tried a few things;
Simply doing this;
TDDATR + 30 DAYS
But it returned this error: Labeled duration not used correctly.
I tried using the DIGITS and SUBSTR commands to create a field in the DDMMYYYY format and then +30 days but got the same error.
Same as above but in the DD/MM/YYYY format - same error.
Using DATE(TDDATR) but all I see is +'s in the field.
Using DATE( ) on the fields created in step 2 and 3 - still get +'s
I've ran out of ideas - any help would be greatly appreciated.
Query/400 lacks a lot of the features that an SQL based interface has.
I'd urge you to consider switching to Query Manager (STRQM) which is a fully SQL based product. You can even convert Query/400 queries to Query Manager queries with the RTVQMQRY command by having the ALWQRYDFN parm set to *YES.
The other option that IBM is pushing is Web Query. Again, fully SQL based and you can convert Query/400 queries into it.
Having said that, the problem is that FLD + 30 DAYS only works when FLD is a DATE data type. Query/400 includes a DATE() function to convert non-date types into date. But it's very limited in that it only works with character fields formatted according to your job defaults. Assuming you're in the US, it'd only work with a character value of '07/01/15'.
You could do a lot of manipulation in Query/400 and end up with a result field that meets DATE()'s requirements. But a better solution would be to create an SQL view over your table and have your numeric date converted into a date data type in the view.
You can find code examples that show how to convert a numeric YYYYMMDD to a actual date data type in the view. However, I'd recommend create a user defined function (UDF) that will do the conversion for you. That will make it much easier to use in the view and to reuse in other places.
If you'd like, there's an open source package called iDate, that includes all the code required for convert to/from date data types.
Download that, install/compile it and your SQL view becomes
select ... idate(TDDATR,'*CCYMD') as TD_DATE
from myfile
The use of days is as follow
Field Expression
CURDATE_30 days(current(date)) + 30
The solution to your problem is: given the field A dec(8,0)
Field Expression
YYYYMMDD_ date(substr(digits(a),5,2)||'/'||
substr(digits(a),7,2)||'/'||
substr(digits(a),3,2))
NEXT_MONTH DAYS(YYYYMMDD_) + 30
Remember to check the date format in your job description. In the example the format is MDY or MM/DD/YY.
More info here
Based on the information here, I created the below 2 fields;
TDDIGI DIGITS(TDDATR)
TDDAT1 SUBSTR(TDDIGI,7,2)||'/'||
SUBSTR(TDDIGI,5,2)||'/'||
SUBSTR(TDDIGI,3,2)
From here I was able to create a date field;
TDDAT2 DATE(TDDAT1)
Which allowed me to perform the necessary calculations.
The format of TDDAT1 is based on your job description which can be found by;
WRKJOB
Option 2
Page down
Date format..: X
Mine was *DMY, so TDDAT1 was formatted based on this.
I have an old app that let's users insert dates so everyone knows when they will be on vacation. Up until now, they had text field where they would enter text as they like ("1.1,5.1,21.1-25.1") or whatever they want as it is simple text field.
This kind of input excludes any chance of filtering or search.
I started playing with Yii not too long ago and this is first time i need to work with multiple dates and or date ranges.
What i need is advice on how to store those dates / date ranges into database? I know Yii has it's way to store single date (i have done it before), but i have no idea if it can work with date ranges and or multiple dates.
If any of you out there had similar problem i would apriciate your advice on how to store those dates and maybe extensions you used etc.
Of course i would like to make it user friendly with date pickers and search capabilities, but i'm taking it step by step. Once i have it stored correctly, searching and filtering wont be huge pain.
What i need is advice on how to store those dates / date ranges into database?
Well that depends on how do you want to use the date range. It depends on what is the criteria for searching. Because If you dont need to search the dates regularly then there may be some dirty ways to accomplish this task.
But if you need to search it frequently then you should make explicit columns for starting and end dates in the database table.By making explicit tables you can search in date ranges easily. for example you can run an sql query like
SELECT * FROM yourtable WHERE startDate<="some date" AND endDate>="some date"
NOTE:
You have to be careful about the format of date in your php code and format of date in database.
If you need to use date range just for calculation purposes then you can use simple php code to accomplish that.
$startDate = '2014-02-20';
$endDate = '2014-03-20';
$inputDate = '2014-02-28';
$start = strtotime($startDate);
$end = strtotime($endDate);
$input = strtotime($inputDate);
bool $isBetween=(($user >= $start) && ($user <= $end));
Yii way:
Actually there is not yii way to work with date range through one window. Actually each framework provide basic independent access to all attributes.That does not mean you cant change the behavior. Yes you can, but you need to code more. There are some extensions which you may find helpful in future
Adding a date range search for CGridView the easy way
How to filter CGridView with From Date and To Date datepicker
Is there a way to store a date in a PostgreSQL db using the Ethiopian date format? I'm trying to store 29th or 30th of February but it throws an error, because in the Julian calendar there's no such thing. Any inputs?
I am not sure that I'll tell you something new but...
Databases are used by programs or by interfaces, I never saw databases that are used by end-user in console with psql.
If you are develop an application, that must display dates in specific calendar, you can store date in PostgreSQL in TIMESTAMP. All operations with dates will work correct in database. But you have to implement conversion from TIMESTAMP into string representation and vice versa in your application manually. If this is most important thing for your application, you will do this.
All queries that must return date you will write with conversion into DOUBLE PRECISION e.g.
SELECT EXTRACT(EPOCH FROM timestamp_field)
This returns DOUBLE PRECISION value that represents timestamp in numerical format.
All date parameters in queries you have convert from numerical presentation in TIMESTAMP using built-in function to_timestamp:
update table_name set
timestamp_fileld = to_timestamp(1384852375.46666)
The other solution is to write psql functions that do this for you directly in queries, but anyway you need to handle each input/output of date fields in queries.
One of my customers would like to have a custom date column, where he could store the year only, a combination of month and year (without the day), or a classic date with day, month and year.
It should be possible to use this field for sorting the data. A "month-year" date should be considered as "01-month-year" for the sort, and a "year" date should be treated as "01-01-year" for the sort.
I could imagine two solutions to that:
Store the date in the standard "day-month-year" format, and keep in a separate column how the date was entered ("year", "month-year", "day-month-year"), so the approximate date can be displayed exactly how it was entered.
Use some sort of custom date column in the postgresql database.
Has anyone experience with that?
You could use date-time functions to extract date components. I don't think it has any sense to create additional columns. Also, some databases allow to create indexes by functions.