i had a problem in VB .NET
first time i get data from Oracle Database
it's fine
after i update something in Oracle Database
My apps keeps the old data before updating
i had try make the new apps, recomplie, and run the same query in oracle
its always has same result in vb
but in oracle, the result show latest data
Note: i run using the same query
i am using this syntax to read data
oracle_command.ExcuteReader()
can anyone gave me some suggestion what must i do?
You should execute a commit after your UPDATE, INSERT, or DELETE operations in Oracle, so that the new data change can be recognized from the VB.NET app side.
Related
I am creating an app it takes data from the server and storing it in SQLite database but each time I run the app the data gets append in the database. I tried onUpgrade() method to drop table and create a new one, but its not working because db_version is the same. But if I change the version manually then its working... but I want solution so that my version changes each time automatically when I run the app....
OR if there is an another alternative please share it....
You are probably didn't understand what is database Upgrade. In two words you upgrade the version of your database when your DB model changed, not the data!
To clear your database for testing purposes use sqlite DROP TABLE or physically delete the file!
If you upgrade the version of the database each time your app starts - you will lose all the database data each time your app starts, so why do you need the database ?
Context:
I have a (legacy) ASP.NET app using a class lib which's data access is calling SPs using ad dal.dbml and its generated code.
I am using VS 2015 Enterprise update 1, have locally installed Microsoft SQL Server 2014 - 12.0.4213.0 (X64) (Build 10586) and SSMS 2014.
Question
When running the Web application the app inserts rows to a table which I recently implemented an insert trigger. How can I debug the actual trigger execution "triggered" by the Web application?
Note: I do know how to interactively debug SPs in SSMS. Now that is not I want, because It is nearly impossible to reproduce and parametrize what the web app does. So I would like to debug via the Web App.
Is this possible at all? (Seems to be a pretty usual need, though I unserstand it requires very complex debugging infrastructure and services)
What you do is you run Profiler to get the typical values being sent when the error occurs.
Then the easiest way I know of to troubleshoot something like this is to take the trigger code out of the trigger and put it in a script using #inserted (and/or #deleted if need be) instead of the pseudotables accessed by the trigger.
The insert the data the stored proc would insert into the table into the #inserted table. Then you can take the trigger step by step and even look at the results of a select that is used in an insert.
The most common error I have found in triggers is that they are set up to handle only one record in inserted rather than multiple records. SO if you find that what your proc would put in for the values you get is one record, that may be the issue. Or you may be missing a required field. IN that case you may need adjust the proc to put in the value or assign a default.
I am working on a firm application in which I need to create a local database on my device.
I create my local database through create statement[ It works well]
Then I use that file and perform insert operation through fire-fox sqlite plugin, I need to insert aprox 2000 rows at a time so I can not use code. I just run insert manually through sqlite plugin in fir-fox.
After that I just use that file in my place of my local database.
When I run select query through my code, It show Exception:java.lang.Exception: Exception: In create or prepare statement in DBnet.rim.device.api.database.DatabaseException: SELECT distinct productline FROM T_Electrical ORDER BY productline: file is encrypted or is not a database
I got the solution of this problem, I was doing a silly mistake by creating a file manually by right click in my RES folder, that is not correct. We need to create the database completely from SQlite plugin, then it will work fine. "Create data base from SQLITE(FIle too) and perform insertion operation from SQLITE, then it will work fine"
This is very rare problem, but i think it might be helpful for someone like me....!:)
You should check to see if there is a version problem between the SQLite used by your Firefox installation and that on the BlackBerry. I think I had the same error when I tried to build a database file with SQLite version 2.
You also shouldn't need to create the database file on the device. To create large tables I use a Ubuntu machine and the sqlite3 command line. Create the file, create the tables, insert the data and build indexes. Then I just copy the file onto the device in the proper directory.
For me it was a simple thing. One password was set to that db. I just used it and prolem got solved.
How to manage database changes while upgrading desktop applications?
We have a SQLite database for one of our desktop apps. The uninstaller keeps the database to be used by the next install. But what if the next install has an updated version? How to keep the data but upgrade the tables?
We use .NET and Linq2sql
Here is how I do this:
In my code I define the version of the database
#define DB_VERSION 2
This version number is incremented every time I make a change to the code that 'breaks' the database ( makes an incompatible change to the schema or the semantics of the db contents )
When the code creates a new database, it executes this SQL command
QueryFormat(L"PRAGMA SCHEMA_VERSION = %d;",DB_VERSION);
Note that this must be AFTER all CREATE TABLE commands have been executed, otherwise sqlite increments SCHEMA_VERSION.
When the code opens an existing database, the first thing it does is
Query(L"PRAGMA schema_version;")
The SCHEMA_VERSION that is returned from this query is compared with the DB_VERSION. If they do not match, then the database was created by a different software version. What happens next depends on the details of what you need. Typically:
database was created by a more recent software: inform user and exit
database was created by older software for which there is an upgrade: offer user option to run upgrade code, or re-initialize database
database was created by older software with no upgrade: offer user option to re-initialize database or exit.
The details of how the upgrade code works depends very much on what you need. In general open the old database AND open a new empty database. Read the old tables, convert the data as required, and write to the new database. Close the dbs. Delete the old db. Rename the new db to the standard db name. Open the new db.
If nothing else, the output of echo .dump | sqlite my_database.sqlite is designed to be extremely portable, even to non-SQLite databases.
Or, if I'm misreading your question, you may want alter table.
I have a number of manually written scripts (.sql) for tables, views and stored procedures that are used from an ASP.NET application. These scripts drop the object and recreates them. I need a way to update the database when the scripts change without deleting the object. For example, when a column is added to an existing table that has rows in it, I would need to update this table with this extra column without losing the rows.
I need a way to "update" the database on a single click (I can hook up the changes using a batch file). Does Visual Studio support this kind of functionality?
If you get Visual Studio Team System - Database Edition 2008 - which is now bundled with "Developer Edition" for free - it handles that. Visual Studio database projects without that edition really just store the static SQL that you want to track. The Database Edition is capable of determining the 'deltas' between your SQL and what's in a target database, generating that script, and executing against your database. You do get the option of reviewing that generated SQL, but by default it is very safe [it won't run if it thinks that there will be any data lost].
Yes - it's called Database Projects.
You can define a Visual Studio Database Projects, have create and change SQL scripts inside it, and then execute those against a database connection of your choice when you need to.
See this blog post here for a great explanation, or read the whole series that the 4 guys from Rolla wrote.