I have an old c# project which currently runs on a SQL CE database. I decided yesterday that I would like to use SubSonic to generate a DAL for me as I have used SubSonic a lot in my other projects (with a standard MS SQL database backend) and I love it's ease of use.
Everything seems fine, I can create and delete records but as soon as I update a record using the Save() method an error it thrown:
Example:
Person person = new Person();
person.Name = "Robert";
person.Save(); // Works fine, record is saved
person.Name = "Robert - Updated";
person.Save(); // Fails with error below
"There was an error parsing the query. [ Token line number = 1, Token line offset = 61, Token in error = SELECT ]"
When I update a record by creating a new Query and setting the QueryType to Update, it also seems to be working as expected.
Any ideas?
Thanks
Try to get hold of the generated SQL to see what gets executed.
My guess is that SubSonic escapes column or table names with [ and ], which is fine for a full-blown SQL Server, but its CE counterpart does not support that.
My guess is that Subsonic is trying to execute several SQL statments in a single command - this is not supported by SQL Compact
Related
I'm using Cosmos DB in Azure. I recently changed the schema to add more information. However, I'm confused because Cosmos uses SQL to query the database. Further, it seems I can't query based on the new schema because I receive the following error messsage:
Message: {"errors":[{"severity":"Error","location":{"start":22,"end":29},"code":"SC2001","message":"Identifier 'comment' could not be resolved."}]}
So I'm wondering is it possible to disable schema validation so I can query on the new comment attribute, without getting this error message.
Further, I'm confused how Cosmos DB can be considered a NoSQL database if it behaves much the same as MySQL.
Edit: The query I am using is
SELECT * FROM c
WHERE comment = ""
The error is not related to the schema, the error is saying your query is incorrectly written.
Following the official documentation (for example, https://learn.microsoft.com/azure/cosmos-db/sql/sql-query-getting-started#query-the-json-items)
The query should be:
SELECT * FROM c
WHERE c.comment = ""
Keep in mind that that query is not checking for documents that do not have the comment property, it's basically filtering documents that do have the comment property with an empty string value.
I am new to CouchDB / PouchDB and until now I somehow could manage the start of it all. I am using the couchdb-python library to send initial values to my CouchDB before I start the development of the actual application. Here I have one database with templates of the data I want to include and the actual database of all the data I will use in the application.
couch = couchdb.Server()
templates = couch['templates']
couch.delete('data')
data = couch.create('data')
In Python I have a loop in which I send one value after another to CouchDB:
value = templates['Template01']
value.update({ '_id' : 'Some ID' })
value.update({'Other Attribute': 'Some Value'})
...
data.save(value)
It was working fine the whole time, I needed to run this several times as my data had to be adjusted. After I was satisfied with the results I started to create my application in Javascript. Now I synced PouchDB with the data database and it was also working. However, I found out that I needed to change something in the Python code, so I ran the first python script again, but now I get this error:
couchdb.http.ResourceConflict: (u'conflict', u'Document update conflict.')
I tried to destroy() the pouchDB database data and delete the CouchDB database as well. But I still get this error at this part of the code:
data.save(value)
What I also don't understand is, that a few values are actually passed to the database before this error comes. So some values are saved() into the db.
I read it has something to do with the _rev values of the documents, but I cannot get an answer. Hope someone can help here.
I created a 4,000-character VARCHAR2 field in an Oracle table. I am inserting string values into the field using LINQ to Entities with Visual Studio 2010, .NET Framework 4, and ODAC 11.2 Release 4 and Oracle Developer Tools for Visual Studio (11.2.0.3.0). When I try to insert a string value greater than 1,999 characters, I get the following inner exception:
Oracle.DataAccess.Client.OracleException
ORA-00932: inconsistent datatypes: expected - got NCLOB
However, I can insert a 4,000 character string value into the field without any issue when doing so using SQL Developer.
There is a known ODAC bug (source #2) in which there is a 2,000 character limit when saving to an XMLTYPE field, but I am not saving to an XMLTYPE field. I have Oracle.DataAccess 2.112.3.0 in my GAC, and I considered updating to release 5 (11.2.0.3.20) of the aforementioned Oracle software, but "Oracle Developer Tools for Visual Studio" is the only component that appears to have been updated from release 4, and I believe that "Oracle Data Provider for .NET 4" is the component that needs updating. In my .NET project, System.Data.Entity and System.Data.OracleClient are both runtime version 4.0.30319.
Anyway, I am just wondering if anyone else has encountered this error, and if so, if any solution has been found - aside from the one in the Oracle forum thread that is linked above that proposes using stored procedures as a workaround. Google tells me that people are encountering this error only when working with XMLTYPE fields, but I can't be the only person who is encountering this error when working with a VARCHAR2 field, can I?
(FWIW, I am also hoping to receive a response to my post as user "997340" in the Oracle forum thread that is linked above. If I receive a useful response, I'll be sure to share the knowledge on this end.)
EDIT: In case it helps, below are the two blocks in my code that are failing. I created the second block when troubleshooting the first, just to see if there was any difference. I get the exception when checking to see if the string values were already inserted (the "if" statements), and when actually inserting the string values (the "AddObject" statements).
1:
if (!(from q in db.MSG_LOG_MESSAGE where q.MESSAGE == msg select q.MESSAGE).Any())
{
db.MSG_LOG_MESSAGE.AddObject(new MSG_LOG_MESSAGE { MESSAGE = msg });
db.SaveChanges();
}
2:
if (!db.MSG_LOG_MESSAGE.Any(q => q.MESSAGE == msg))
{
db.MSG_LOG_MESSAGE.AddObject(new MSG_LOG_MESSAGE { MESSAGE = msg });
db.SaveChanges();
}
APRIL 3 UPDATE:
I was able to trace the SQL that is being sent to Oracle from the "if" statement in the first code block above. Here it is:
SELECT
CASE WHEN ( EXISTS (SELECT
1 AS "C1"
FROM "SEC"."MSG_LOG_MESSAGE" "Extent1"
WHERE ("Extent1"."MESSAGE" = :p__linq__0)
)) THEN 1 WHEN ( NOT EXISTS (SELECT
1 AS "C1"
FROM "SEC"."MSG_LOG_MESSAGE" "Extent2"
WHERE ("Extent2"."MESSAGE" = :p__linq__0)
)) THEN 0 END AS "C1"
FROM ( SELECT 1 FROM DUAL ) "SingleRowTable1" ;
Unfortunately, the DBA that I worked with did not provide me with the value of the "p_linq_0" parameter, but as previously stated, when it is over 1,999 characters, an exception occurs. (When this SQL was traced, I passed a 4,000-character string as the parameter, and of course an exception occurred.) The DBA also mentioned something about certain SQL clients - such as SQLPlus - not being able to handle VARCHAR2s over 2,000 characters. I did not entirely follow. Whether using SQLPlus, SQL Developer, or any other tool, Oracle is still going to be querying a 4,000-character VARCHAR2 field. Plus, my magic number is 1,999 characters; not 2,000 characters. Did the DBA perhaps mean there is a limitation with how many characters can be in a parameter? More importantly, when I execute this SQL in SQL Developer and I enter a 4,000-character string for the parameter, it works perfectly. So I am still utterly confused about why it is not working via LINQ to Entities. I also tried the following code in my program to run a similar query with a 4,000-character string in the "msg" variable, which worked perfectly as well:
using Oracle.DataAccess;
using Oracle.DataAccess.Client;
using System.Data;
...
OracleConnection conn = new OracleConnection("Data Source=[MASKED];User Id=[MASKED];Password=[MASKED]");
conn.Open();
OracleCommand cmd = new OracleCommand();
cmd.Connection = conn;
cmd.CommandText = "SELECT message FROM msg_log_message WHERE message = '" + msg + "'";
cmd.CommandType = CommandType.Text;
OracleDataReader dr = cmd.ExecuteReader();
dr.Read();
string result1 = dr.GetString(0);
conn.Dispose();
For now, I am still pointing fingers at ODAC being buggy as it pertains to LINQ to Entities...
The latest ODP.NET documentation - for "11.2 Release 5 Production (11.2.0.3.0)" from September 2012 - states the following known issue under the "Entity Framework Related Tips, Limitations and Known Issues" section, which addresses the error from the "if" statements in the question's code blocks:
An "ORA-00932 : inconsistent datatypes" error can be encountered if a string of 2,000 or more characters, or a byte array with 4,000 bytes or more in length, is bound in a WHERE clause of a LINQ/ESQL query. The same error can be encountered if an entity property that maps to a BLOB, CLOB, NCLOB, LONG, LONG RAW, XMLTYPE column is used in a WHERE clause of a LINQ/ESQL query.
Older ODP.NET documentation - for "Release 11.2.0.3.0 Production" from May 2011 - states the same known issue, so apparently this has been a known issue for a while.
Neither of the aforementioned documentation mentions encountering the same error from the "AddObject" statements in the question's code blocks, but that issue is very similar to another known issue for XMLType fields that is mentioned:
An "ORA-00932: inconsistent datatypes: expected - got NCLOB" error will be encountered when trying to bind a string that is equal to or greater than 2,000 characters in length to an XMLType column or parameter. [Bug 12630958]
Im fairly new to ASP.NET MVC 3, and to coding in general really.
I have a very very small application i want to upload to my webhosting domain.
I am using entity framework, and it works fine on my local machine.
I've entered a new connection string to use my remote database instead however it dosen't really work, first of all i have 1 single MSSQL database, which cannot be de dropped and recreated, so i cannot use that strategy in my initializer, i tried to supply null in the strategy, but to no avail, my tables simply does not get created in my database and thats the problem, i don't know how i am to do that with entity framework.
When i run the application, it tries to select the data from the database, that part works fine, i just dont know how to be able to create those tabes in my database through codefirst.
I could probaly get it to work through manually recreating the tables, but i want to know the solution through codefirst.
This is my initializer class
public class EntityInit : DropCreateDatabaseIfModelChanges<NewsContext>
{
private NewsContext _db = new NewsContext();
protected override void Seed(NewsContext context)
{
new List<News>
{
new News{ Author="Michael Brandt", Title="Test News 1 ", NewsBody="Bblablabalblaaaaa1" },
new News{ Author="Michael Brandt", Title="Test News 2 ", NewsBody="Bblablabalblaaaaa2" },
new News{ Author="Michael Brandt", Title="Test News 3 ", NewsBody="Bblablabalblaaaaa3" },
new News{ Author="Michael Brandt", Title="Test News 4 ", NewsBody="Bblablabalblaaaaa4" },
}.ForEach(a => context.News.Add(a));
base.Seed(context);
}
}
As i said, im really new to all this, so excuse me, if im lacking to provide the proper information you need to answer my question, just me know and i will answer it
Initialization strategies do not support upgrade strategies at the moment.
Initialization strategies should be used to initialise a new database. all subsequent changes should be done using scripts at the moment.
the best practice as we speak is to modify the database with a script, and then adjust by hand the code to reflect this change.
in future releases, upgrade / migration strategies will be available.
try to execute the scripts statement by statement from a custom IDatabaseInitializer
then from this you can read the database version in the db and apply the missing scripts to your database. simply store a db version in a table. then level up with change scripts.
public class Initializer : IDatabaseInitializer<MyContext>
{
public void InitializeDatabase(MyContext context)
{
if (!context.Database.Exists() || !context.Database.CompatibleWithModel(false))
{
context.Database.Delete();
context.Database.Create();
var jobInstanceStateList = EnumExtensions.ConvertEnumToDictionary<JobInstanceStateEnum>().ToList();
jobInstanceStateList.ForEach(kvp => context.JobInstanceStateLookup.Add(
new JobInstanceStateLookup()
{
JobInstanceStateLookupId = kvp.Value,
Value = kvp.Key
}));
context.SaveChanges();
}
}
}
Have you tried to use the CreateDatabaseOnlyIfNotExists
– Every time the context is initialized, database will be recreated if it does not exist.
The database initializer can be set using the SetInitializer method of the Database class.If nothing is specified it will use the CreateDatabaseOnlyIfNotExists class to initialize the database.
Database.SetInitializer(null);
-
Database.SetInitializer<NewsContext>(new CreateDatabaseOnlyIfNotExists<NewsContext>());
I'm not sure if this is the exact syntax as I have not written this in a while. But it should be very similar.
If you are using a very small application, you maybe could go for SQL CE 4.0.
The bin-deployment should allow you to run SQL CE 4.0 even if your provider doesn't have the binaries installed for it. You can read more here.
That we you can actually use whatever initializer you want, since you now don't have the problem of not being able to drop databases and delete tables.
could this be of any help?
I have an MS Access database, which I have converted to an SQLite database. I have SubSonic setup and working, and I can pull data out of the database successfully into a WinForms app using ActiveRecord. All except for one table.
I get a FormatException, "String was not recognized as a valid DateTime". The format of the date column in the database is DD/MM/YYYY.
I'm not even trying to do anything too complicated:
var allOrders = order.All();
foreach (order o in allOrders)
{
listBox1.Items.Add(string.Format("{0} - {1}", o.OrderDate.HasValue ? o.OrderDate.Value.ToShortDateString() : string.Empty, o.Product));
}
I'm not exactly sure why the problem is manifesting in the first place :(
SQLite has "interesting" ways of formatting dates - you have to be very, very sure that you're getting back what you think you are because normally it's not DD/MM/YYYY - it's the opposite if I recall.