Can any one tell me how to implement for update in oracle using NHibernate? Are there any pre defined clauses for this? If not please tell me how can I implement it.
Read this chapter.
Basically, you need to get your poco using ISession.Get(Of Poco)(id, LockMode.Upgrade).
As a result, that should issue a SELECT ... FROM Poco Where Id = ? FOR UPDATE.
You can also invoke using LockMode.UpgradeNoWait to get a equivalent FOR UPDATE NOWAIT SQL Statement
Related
New to Entity Framework Core. How do I clear all the rows from a table?
I searched around and found the following solution:
_context.Database.ExecuteSqlCommand("TRUNCATE TABLE[TableName]");
Unfortunately using ExecuteSqlCommand throws a compiler error.
Am I missing a namespace or is there another way to do this?
Thanks, JohnB
ExecuteSqlCommand is Obsolete,you can see the details here.
For the execution of SQL queries using plain strings, use ExecuteSqlRaw instead. For the execution of SQL queries using interpolated string syntax to create parameters, use ExecuteSqlInterpolated instead.
So you can use:
_context.Database.ExecuteSqlRaw("TRUNCATE TABLE[TableName]");
I know that we can easily apply filters to query with additional where conditions with NHibernate, but is it possible to apply a filter when doing an update or delete?
If it is, how can I achieve that?
Yes it is possible, using HQL (Hibernate Query Language)
Here's an example of a batch update
IQuery updateQuery = this.Session.CreateQuery("update TransferItem set Status = :newStatus where Status = :oldStatus")
.SetParameter("oldStatus", DownloadStatus.Active)
.SetParameter("newStatus", DownloadStatus.Queued);
updateQuery.ExecuteUpdate();
NHibernate applies the configured mappings to create and run the following SQL:
update cms_TransferItem set Status=#p0 where Status=#p1
Here's an example of a batch delete
IQuery deleteQuery = this.Session.CreateQuery("delete TransferItem ti WHERE ti.Status = :statusToGo")
.SetParameter("statusToGo", DownloadStatus.Completed);
deleteQuery.ExecuteUpdate();
Which executes SQL like this:
delete from cms_TransferItem where Status=#p0
You might ask, if you have to work with a query language, why not just write raw SQL? When you use HQL you are working with the conceptual business objects that the rest of the .NET code is working with. The benefits of an ORM tool is that, for much of the code, the database tables and object-to-table mappings are abstracted away. With HQL you are continuing to interact with the object layer, rather than directly with the database tables.
I need to dynamically create a table using a Java method and tranform all its rows into a list of Mapping class objects. The questions are..
Is there a way to execute CREATE TABLE query dynamically?
I saw some examples using doInHibernate() but it didn't work when I tried it. Can I do this without the particular method?
You could just execute a native sql query: session.createSQLQuery("create table .....").executeUpdate(); where "session" is your Hibernate session.
If you already have the mapping files, though, you can just set the hibernate.hbm2ddl.auto property in your hibernate configuration to generate the schema based on the mapping files.
Try this:
session.createSQLQuery(query).executeUpdate();
another possibility would be:
createStatement().execute(someddl);
I tried session.createSQLQuery("ALTER TABLE People MODIFY address VARCHAR(1000);").executeUpdate();
but this throws org.hibernate.exception.SQLGrammarException: could not execute native bulk manipulation query
After a lot of googling, the recommendation is to use HQL instead of SQL query to do bulk updates. Not sure how to use HQL to accomplish this. There seems to be no decent HQL documentation for updating column length in a table.
Thanks so much for the help.
I suggest you to run this native SQL query via session.connection().
See section 16.2.2.1. Rules/limitations for using stored procedures of Chapter 16. Native SQL, it's near your ALTER query.
All the rest depends on your database vendor. Good Luck!
I could not find a way. Looks like a limitation. I added a new field and copied over data from old field at start-up!
I have this problem.
I have a module (module 1) that use Nhibernate to manage entity persistence; this module interacs with an other module (module 2).
The "module 2" allows to generate dynamically native SQL where clause. Now I would use it to manage filter operation in "module 1".
Which is the bast way to do it?
Is possible get the native SQL Select from "Nhibernate" entity without write manually it?
Then, if I get the native SQL Select statement I can easily apply where. Is there a better way?
Otherwise, is possible translate navite SQL statement to HQL statement?
i don't exactly understand your problem but it seems to me that filters is what you want
Really I had a old procedure that build where clause and return it in SQL Native Format (according to specific preset)...now to solve my problem I have modified the procedere to obtain the where clause in HQL Format so apply it to my entity. So it works.