I am exploring the SQL queries on JSON documents that has a timestamp field called lastVisited.
Here's an example:
"lastVisited" : "2020-11-21T20:33:39.8125"
My application would like to extract individual component of the timestamp. For example, we want to individually extract the year, month, day, hour, and minute.
Does Oracle NoSQL Database support functions that do that?
There are several timestamp query functions for this: year(), month() etc.
See the documentation for all the details.
Related
I am beginner in Backend technology and I am developing one query in Typeorm QueryBuilder + PostgreSQL.
My query is look like this :
But I can't convert my timestamp into following format. Can anyone who has expertise in it, please help me to select all records with timestamp in specific format.
I am suffering this things from last two days but still not find any solution. Actually I want to compare this date format in having clause. so I want to first select that date format then I can use that same method to compare column with current date and previous dates.
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.
I have a table called "Publicholidays" where in dates are stored as Varchar.
My query should fetch all values from say table xxxx between the user selected dates that exclude the weekends(sat,sun), public holidays. I am new to DB2 so can anyone suggest me ideas please
Note: in DB dates are stored as String.
Mistake #1 - Storing dates as strings. Let's hope you have at least stored them YYYY-MM-DD and not MM-DD-YYYY.
Mistake #2 - Instead of a "Publicholidays" table, you need a Calendar (aka Dates or date conversion) table. It should have a record for every day along with a few flag columns BUSINESS_DAY, WEEKEND, PUBLIC_HOLIDAY. Alternatively, you could have a single DAY_TYPE column with values for business day, weekend and holiday. You'll also want to have a STRING_DATE column to make conversion between your string date and a true date easier.
Google SQL Calender table and you'll find lots of examples and discussions.
Lastly, strongly consider fixing your DB to store dates in a date column.
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.