I am using grails/groovy, and from my controller I am currently doing this for retrieving field from Mysql table containing datetime field
SimpleDateFormat Sformat = new SimpleDateFormat("yyyy-MM-dd");
String format_datenow = Sformat.format(new Date());
String format_dateprevious = Sformat.format(new Date() -31);
String markerCalcQuery =
"select sum(trans_cnt) as t_cnt, location from map2_data where fdate between '"+format_dateprevious+"' and '"+format_dateprevious+"' and res_id = "+res_id+" group by map2_data.location";
res_row=gurculsql.rows(markerCalcQuery);
The above query fails on Oracle11g with error
ORA-01843: not a valid month.
The error I feel is because MySQL stores date in this format: 2011-12-28 02:58:26 and Oracle stores date like this: 28-DEC-11 02.58.26.455000000 PM
How do I make the code generalised, one way is to make the database in Oracle store the date in the same format which I am thinking the way to handle this rather than from the code. If yes, how to change date format in the Oracle db?
Can I specify the format in the grails domain class for map2_data so that no matter what database it is we will have the datetime in the same format.
For several reasons (one being to code database independent - which is basically what you'd need ;-)), it is better to avoid creating SQL statements in your code. Try to use the Grails criteria DSL, e.g. something like
def criteria = YourDomainObject.createCriteria()
criteria.get {
between ('fdate', new Date()-31, new Date())
projections {
sum('trans_cnt')
groupProperty('location')
}
}
(ontested, but should help you get started).
If for some reason you can't use the criteria API, try the fallback to HQL (Hibernate Query Language). I'd always try to avoid to write plain SQL.
In Oracle, dates have their own type, they aren't strings. If you have a string, you should convert it to a date using the TO_DATE function.
String format_datenow = "TO_DATE('" + Sformat.format(new Date()) + "', 'YYYY-MM-DD')";
To make it work also in MySQL, you can create a stored function named TO_DATE that just returns its first argument.
Related
I have a cosmos db collection. I need to query all documents and return them in order of creation date. Creation date is a defined field but for historical reason it is in string format as MM/dd/yyyy. For example: 02/09/2019. If I just order by this string, the result is chaos.
I am using linq lambda to write my query in webapi. I have tried to parse the string and try to convert the string. Both returned "method not supported".
Here is my query:
var query = Client.CreateDocumentQuery<MyModel>(CollectionLink)
.Where(f => f.ModelType == typeof(MyModel).Name.ToLower() && f.Language == getMyModelsRequestModel.Language )
.OrderByDescending(f => f.CreationDate)
.AsDocumentQuery();
Appreciate for any advice. Thanks. It will be huge effort to go back and modify the format of the field (which affects many other things). I wish to avoid it if possible.
Chen Wang.Since the order by does not support derived values or sub query(link),so you need to sort the derived values by yourself i think.
You could construct the MM/dd/yyyy to yyyymmdd by UDF in cosmos db.
udf:
function getValue(datetime){
return datetime.substring(6,10)+datetime.substring(0,2)+datetime.substring(3,5);
}
sql:
SELECT udf.getValue(c.time) as time from c
Then you could sort the array by property value of class in c# code.Please follow this case:How to sort an array containing class objects by a property value of a class instance?
I am trying to update the database with the following query, but I am having difficulty formatting dates. What should I do?
string query = "update employee_info set FirstName ='txtfirstName.Text',LastName ='txtlastName.Text' ,Address1='txt_address', City = 'combo_city' ,Country='combo_Country',ReportsTo='txt_reportTo' WHERE Bday='dtp_birthDate.Value.ToShortDateString()' and HireDate='dtp_hireDate.Value.ToShortDateString()'";
You should use a parameterized query instead. This gets you around having to format the strings for the where clause correctly and also prevents you from being vulnerable to SQL injection attacks (https://en.wikipedia.org/wiki/SQL_injection)
Something like this (the below sample has a shortened version of your query and lacks setting up a db connection).
strQuery = "update employee_info set FirstName=#firstName, LastName=#lastName WHERE Bday=#birthDate and HireDate=#hireDate";
cmd = new SqlCommand(strQuery);
cmd.Parameters.AddWithValue("#firstName", txtfirstName.Text);
cmd.Parameters.AddWithValue("#CompanyName", txtLastName.Text);
cmd.Parameters.AddWithValue("#birthDate", dtp_birthDate.Value);
cmd.Parameters.AddWithValue("#hireDate", dtp_hireDate.Value);
cmd.ExecuteNonQuery();
We have some data in a DataTable and we are using the query like this to get what we need.
IEnumerable<Results> subResult = from query in datatable.AsEnumerable()
select new Results
{
Name = query.Field<string>("Name"),
Date = query.Field<DateTime?>("Date")
}
This above query returns what i need but date in full format (Ex: m/dd/yyyy hh:min:sec am/pm) but we need only date part of it(only mm/dd/yyyy need to be pulled in). When looked in the properties of this, couldn't find an implicit way to get it, please help me in getting this result. Thanks.
The DateTime class has all the properties you just mentioned. You should try to fix your display with the ToString("anyformatyouwant") formats.
What about this?
Date = query.Field<DateTime?>("Date").Date
This will give you just the date part:
IEnumerable<Results> sub-result= from query in datatable.AsEnumerable()
where new Results
{
Name = query.Field<string>("Name"),
Date = query.Field<DateTime?>("Date").Date
}
However if you just want to display the date somewhere (meaning you're not using this to do date grouping, etc. then I would just specify the display format in your UI layer.
AFAIK there is no Date Class in .net, if you want pure date you should write a Class for that, otherwise you can pull out the part as a string
DateTime.Now.Date.ToString("yyyy/MM/dd")
gives you the current date in string type, but if you get the .Date part it gives you a DateTime object which still has a time part showing AM 12:00:00:0 blah blah
I'm using the Mongo shell to query my Mongo db. I want to use the timestamp contained in the ObjectID as part of my query and also as a column to extract into output. I have setup Mongo to create ObjectIDs on its own.
My problem is I can not find out how to work with the ObjectID to extract its timestamp.
Here are the queries I am trying to get working. The 'createdDate' field is a placeholder; not sure what the correct field is:
//Find everything created since 1/1/2011
db.myCollection.find({date: {$gt: new Date(2011,1,1)}});
//Find everything and return their createdDates
db.myCollection.find({},{createdDate:1});
getTimestamp()
The function you need is this one, it's included for you already in the shell:
ObjectId.prototype.getTimestamp = function() {
return new Date(parseInt(this.toString().slice(0,8), 16)*1000);
}
References
Check out this section from the docs:
Extract insertion times from _id rather than having a separate timestamp field
This unit test also demostrates the same:
mongo / jstests / objid6.js
Example using the Mongo shell:
> db.col.insert( { name: "Foo" } );
> var doc = db.col.findOne( { name: "Foo" } );
> var timestamp = doc._id.getTimestamp();
> print(timestamp);
Wed Sep 07 2011 18:37:37 GMT+1000 (AUS Eastern Standard Time)
> printjson(timestamp);
ISODate("2011-09-07T08:37:37Z")
This question is helpful to understand of how to use the _id's embedded timestamp in query situations (refers to the Mongo Extended JSON documentation). This is how it's done:
col.find({...,
'_id' : {'$lt' : {'$oid' : '50314b8e9bcf000000000000'}}
})
finds documents created earlier than the one that's given by oid. Used together with natural sorting and limiting you can utilize BSON _ids to create Twitter-like API queries (give me the last OID you have and I'll provide twenty more)
In python you can do this:
>>> from bson.objectid import ObjectId
>>> gen_time = datetime.datetime(2010, 1, 1)
>>> dummy_id = ObjectId.from_datetime(gen_time)
>>> result = collection.find({"_id": {"$lt": dummy_id}})
I think, ObjectId.from_datetime() - its a useful method of standard bson lib
Maybe other language bindings have alternative builtin function.
Source: http://api.mongodb.org/python/current/api/bson/objectid.html
To use the timestamp contained in the ObjectId and return documents created after a certain date, you can use $where with a function.
e.g.
db.yourcollection.find( {
$where: function() {
return this._id.getTimestamp() > new Date("2020-10-01")
}
});
The function needs to return a truthy value for that document to be included in the results. Reference: $where
Mongo date objects can seem a bit peculiar though. See the mongo Date() documentation for constructor details.
excerpt:
You can specify a particular date by passing an ISO-8601 date string with a year within the inclusive range 0 through 9999 to the new Date() constructor or the ISODate() function. These functions accept the following formats:
new Date("<YYYY-mm-dd>") returns the ISODate with the specified date.
new Date("<YYYY-mm-ddTHH:MM:ss>") specifies the datetime in the client’s local timezone and returns the ISODate with the specified datetime in UTC.
new Date("<YYYY-mm-ddTHH:MM:ssZ>") specifies the datetime in UTC and returns the ISODate with the specified datetime in UTC.
new Date(<integer>) specifies the datetime as milliseconds since the Unix epoch (Jan 1, 1970), and returns the resulting ISODate instance.
I am trying to perform the following linq to entities query-
var data = DataContext.Employee.Where(e=>e.Date.Year>1986).ToList();
Now the problem is that Date field is a nullable DateTime field and I can't access Year property and on the database side I can't change legacy code! ....anyways is there anyway possible to use the year property?
var data = DataContext.Employee
.Where(e=>e.Date.HasValue && e.Date.Value.Year>1986).ToList();
Note that this will not include Employees without a date in the list.