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.
Related
How to use to_date function in oracle-sqldeveloper to convert a string
May 1 2019 12:00 to date datatype? Does Date in SQL store time too,
or it only stores date? I tried using the to_date function with some
format but it always removes the time part.
If the time is not possible in Date datatype what could be a good alternative?
You can convert your date to a string with (assuming 24-hour values, which seems likely as you don't have an AM/PM marker):
to_date('May 1 2019 12:00', 'Mon DD YYYY HH24:MI', 'nls_date_language=English')
The format elements are in the documentation. I've included the optional third argument to to_date() because your month name has to be interpreted in English, regardless of your session settings.
it always removes the time part
Oracle dates always have both date and time parts, even if the time is set to midnight. You're probably seeing the result of that query as '01-MAY-19'.
Dates don't have any intrinsic human-readable format; Oracle uses its own internal representation, which you generally don't need to worry about.
In most clients and IDEs the session NLS_DATE_FORMAT setting is used to display native dates as strings. For historic reasons that still defaults to DD-MON-YY, despite Y2K, during database creation. it can be changed at database level, and sessions will then inherit that. But each session can override it, e.g. by issuing:
alter session set nls_date_format = 'YYYY-MM-DD HH24:MI:SS'
You can also explicitly convert a date value back to a string, and specify which format elements you want to include, via a to_char() call. Only do that when displaying a value - if you're storing dates or passing them around to functions, always do that as the proper date data type, not as strings. (If you have to pass them outside the database as strings, e.g. to a remote API, you'd usually want to use an ISO-8601 format).
db<>fiddle showing the default output, explicitly formatted as a string (again, for display only - do not store or manipulate dates as string), and with the session format modified.
In SQL Developer you can also go to Tools->Preferences->Database->NLS and change the 'Date format' there - that setting will then apply when you create new sessions, without having to issue alter session each time.
I'm using Seekwell to connect my AWS postgres database to Sheets.
I think I'm converting my dates to standard 'date' (YYYY-MM-DD) format in the code, eg.
date(date_trunc('day', u.created_at::date)) Date_Created
However, when the query is run, my dates are iso 8601, eg.
2018-05-16T00:00:00.000Z
Of course, given that my results are going into Google Sheets, I can always convert those dates there in sheets, but that adds a layer of complexity that is hard to manage.
How can I make sure the dates are formatted correctly before the results land in sheets?
Michael from Seekwell tells me this is:
a bit of bug with how JDBC handles dates in the background. You're on Postgres, right? This should work from within the add-on:
to_char(your_date_column, 'YYYY-MM-DD')
Sheets will recognize that result as a date.
This worked.
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 am building a map in CartoDB which uses Postgres. I'm simply trying to display my dates as: 10-16-2014 but, haven't been able to because Postgres includes an unneeded timestamp in every date column.
Should I alter the column to remove the timestamp or, is it simply a matter of a (correct) SELECT query? I can SELECT records from a date range no problem with:
SELECT * FROM mytable
WHERE myTableDate >= '2014-01-01' AND myTableDate < '2014-12-31'
However, my dates appear in my CartoDB maps as: 2014-10-16T00:00:00Z and I'm just trying to get the popups on my maps to read: 10-16-2014.
Any help would be appreciated - Thank you!
You are confusing storage with display.
Store a timestamp or date, depending on whethether you need time or not.
If you want formatted output, ask the database for formatted output with to_char, e.g.
SELECT col1, col2, to_char(col3, 'DD-MM-YY'), ... FROM ...;
See the PostgreSQL manual.
There is no way to set a user-specified date output format. Dates are always output in ISO format. If PostgreSQL let you specify other formats without changing the SQL query text it'd really confuse client drivers and applications that expect the date format the protocol specifies and get something entirely different.
You have two basic options.
1 Change the column from a timestamp to a date column.
2 Cast to date in your SQL query (i.e. mytimestamp::date works).
In general if this is a presentation issue, I don't usually think that is a good reason to muck around with the database structure. That's better handled by client-side processing or casting in an SQL query. On the other hand if the issue is a semantic one, then you may want to revisit your database structure.
Running a SELECT against the AS400 using the IBMDA400 OleDb provider appears to return dates as string values, SSRS just laughs at you when you try and apply a date format to the field. I've tried a simple CAST in the SELECT to no avail.
How can I get an actual DBTYPE_DBDATE struct back from the iSeries OleDb provider?
I should mention that the dates in question are all being returned by a UDF with a type of DATE. IBM appears to map DATE type into a DBTYPE_STR OleDb type.
The field(s) in the table(s) are probably not defined as a date type. You will need to convert them using the DATE function as part of the query.
You can use the DSPFFD command, the Navigator, or query the SYSIBM.SQLCOLUMNS table to view the field definitions.
UPDATE
After further testing with the IBMDA400 provider I found the Convert Date Time To Char property hidden away in the OLE DB Technical Reference installed as part of the Programmer's Toolkit with Access. The default value is TRUE. Set Convert Date Time To Char=FALSE in the connection string or properties to disable this 'feature'.
Here's a quick VBA test:
Set cn = CreateObject("ADODB.Connection")
cn.Open "Provider=IBMDA400;Data Source=...;User ID=...;Password=...;Convert Date Time To Char=FALSE"
Set rs = cn.Execute("SELECT DATE(NOW()) FROM SYSIBM.SYSDUMMY1")
MsgBox "Returned ADO type: " & rs.Fields(0).Type
See MSDN: DataTypeEnum for the possible ADO data types. adDBDate is 133.
IBM i Access for Windows OLE DB Technical Reference
IBM i OLE DB provider functions > Special Properties
Convert Date Time To Char
Specifies conversion of DB2 for IBM i Date, Time, and Timestamp data types to corresponding PC data types and vice versa.
Settings and Return Values
Sets or returns one of the following string values. The default value is "TRUE".
"TRUE"
DB2 for IBM i Date, Time, and Timestamp data types are treated as character strings. When reading IBM i data, these values are converted to character strings. When writing data to the system, character strings are expected as input for these values. The supported character string format for the Date data type is ISO format: yyyy-mm-dd. The supported character string format for the Time data type is the earlier version of the ISO format: hh.mm.ss. The supported character string format for the Timestamp data type is: yyyy-mm-dd-hh.mm.ss.nnnnnn.
"FALSE"
DB2 for IBM i Date, Time, and Timestamp data types will be converted to PC Date, Time, and Timestamp data types. Care should be taken when using this value in an environment that only supports the Variant Date data type (such as Visual Basic). You may encounter unexpected errors due to truncation or overflow caused by the limitations of the Variant Date data type.
Following are additional considerations when Convert Date Time To Char is FALSE.
The variant Date data type, which is actually a timestamp, does not support micro-seconds - the precision of the DB2 for IBM i timestamp. The OLE DB provider will truncate the fractional timestamp without reporting an error. For example, 1990-03-02-08.30.00.100517 will become 1990-03-02-08.30.00.000000. All updated or inserted timestamp values will have 0 micro-seconds.
Leap second overflow error. The OLE DB timestamp allows up to two leap seconds (a value of 60 or 61). DB2 for IBM i supports a maximum value of 59. An overflow error is returned if leap seconds are set.
The variant Date data type does not support the data limits of an ISO date or timestamp. The value "0001-01-01", used as a default date in many databases, including DB2 for IBM i, will cause an overflow.
DB2 for IBM i supports a time value of 24:00:00 for certain older formats of the TIME data type. The OLE DB provider will convert values of 24:00:00 to 00:00:00 without any error message or warning.
Typically for VB variant, a date value of 1899-12-30 (which is a 0 date) is used to imply a Time only variant date. A time of Midnight (00:00:00) is used to imply a Date only variant date.
Remarks
This custom property is available on the ADO connection object. The property is read/write when the connection is closed and read-only when the connection is open.
Delphi example
<connection>.Provider := 'IBMDA400';
<connection>.Properties('Convert Date Time To Char') := "TRUE";
OR
<connection>.Open('Provider=IBMDA400;Data Source=SystemA;Convert Date Time To Char =TRUE', 'Userid', 'Password');
PowerBuilder example
<connection>.Provider = "IBMDA400"
SetProperty(<connection>), "Convert Date Time To Char", "TRUE")
OR
<connection>.Open("Provider=IBMDA400;Data Source=SystemA;Convert Date Time To Char=TRUE", "Userid", "Password")
Visual Basic example
<connection>.Provider = "IBMDA400"
<connection>.Properties("Convert Date Time To Char") = "TRUE"
AND/OR
<connection>.Open "Provider=IBMDA400;Data Source=SystemA;Convert Date Time To Char=TRUE", "Userid", "Password")
It appears the correct answer is, you can't. No way, no how, does the IBMDA400 provider map any type into a DBTYPE_DBDATE.
What you can do is use the DateValue() SSRS function to convert the returned DBTYPE_STR value to a date/time serial. From there the format functions will work on it.
I didn't have a problem, here in North America, with the DateValue() function directly interpreting the returned DBTYPE_STR value, however, this could be an issue in other locales due to date format differences.