Most Efficient Way To Handle Continual Database Access
Mar 6, 2009
Whats the best way to handle the connection to a db when it's accessed often? I have an app where the user selects an item from a drop down list(call to the db) and then a picture of the item is returned along with it's relevant information(another call to the db). Small application but basically every action results in a call to the database. Should i just be filling like a global dataset and then accessing the information from there(if thats possible)? The database is stored locally(currently an Access Db but will be SQL in the future)
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Nov 9, 2011
I am looping through my dataset to save my database, I thought this might not be the best way. Is there a more resource efficient of doing it?
For i As Integer = 0 To CO.Tables("CO_Del").Rows.Count - 1 'CO is my DataSet
dbCommand.Parameters.Clear()
AddInParameter(dbCommand, "@IsDelete", DbType.Boolean, 0, DBNull.Value)[code].......
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Jan 15, 2010
I have a Page class and a PageCollection class in a 3d party ORM framework. I can fill the PageCollection based on parameters (pageid, parentid, url etc..) (SQL query). But I need the data multiple times around the ASP.NET MVC website (Sitemap, Authentication), so I chose to load all pages 1 time and reference that (global) collection.
GlobalClass.Pages //is PageCollection containing all pages
I have now created functions which return a temporary subcollection or single entity based on the parameters mentioned before (pageid, parentid, url etc..).
GlobalClass.Pages.GetByPageId(id) //returns single page entity
GlobalClass.Pages.GetByParentId(parentid) //returns subcollection
The site however got very slow.
cache the subcollections (GetByParent())? create internal hash-lookup tables for the collection? Something else...?
Namespace BLL
Public Class PageCollection
Inherits CustomCollectionBase
[Code]....
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Jan 8, 2011
I was wondering what was the best way to search a database. Is it possible to perform bubble sort etc or any sort of binary search to the database instead of doing a linear search. If so how would I go about doing this through an Sql statement.
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Mar 15, 2012
When I finish creating a new table in MS Access a pop-up dialog appears and offers to type in "Table name" and save it.Visual basic code that fills the table name and selects "Ok" button automatically?
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Jun 4, 2011
I can save my data to access database and in the access database field I set it to date/time.But problem is when I get the value out from the database.. the format is always month/day/year hour:minutes:seconds example today: 5/2/2011 12:00:00..How to get the value into listview becoming May/2/2011 without the hour..Here's my code to get it from database ListView1.Items(i).SubItems.Add(dt.Rows(i)(14).ToString).The second problem is.When I would like to edit, how can the datetimepicker get the listview value ? [code] info: using access 2003 (.mdb) the Date of Birth field has been set into Date/Time.
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Oct 10, 2009
I made a program that is started and running in memory and minimized to the system tray.
When it is first launched it registers global hot keys in windows.These hot keys are used for resizing the current focused window. I'm trying to use it so you can hotkey windows to resize to half the screen, a third of the screen, etc... For instance, if I have two notepads open and notepad 1 is focused and I hit Ctrl+Shift+LeftArrow it will resize notepad1 to the left and half the size of the screen. I have notepad 2 focused and Hit Ctrl+Shift+RightArrow and resize notepad2 to the right side of the screen. So, I can easily see both windows at once.Now, I can successfully get the focused window handle when the hot key is pressed. I'm stuck at this point.
I can use the Windows API call:
[code]...
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Jan 17, 2011
I am trying to get a list of files using this line of Dim files() As String = IO.Directory.GetFiles("D:", "*.*", SearchOption.AllDirectories)But it errors out on folders that are inaccessible, like the RecycleBin folder & the program stops. So how do I get a list of files in all folders, while skipping the inaccessible one
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Dec 10, 2009
I am writing an audit file that is writing the username, time, and the old/changed values of several variables in the application for each user when they use my application. It is using a FileStream and StreamWriter to access the audit file. All audits for each user will be written to the same file. The issue is that when two users are updating this audit file at the same time, the "old value" of each of the variable is mixing up between the users.
Dim fs As FileStream
Dim w As StreamWriter
Public Sub WriteAudit(ByVal filename As String, ByVal username As String, ByVal oldAddress As String, ByVal newAddress As String, ByVal oldCity As String, ByVal newCity As String)
[code]....
This lives in an AuditLogger class, which is referenced via an instance variable (re-allocated each time the function is accessed).
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Jun 29, 2011
I have the membership provider setup and its currently pointing to a SQL database on my machine. The role based access works and I have a menu that is security trimmed. The user can only get to pages that they have access to.When an anonymous user tries to get to a page that they dont have access to it brings them to a login page so that they can login. That is fine. But when a logged in user tries to get to a page they dont have access to(Usually by typing in a URL) it brings them to the login page again asking them to login(except there already logged in. I'd like to either take them to a different page or somehow tell them they don't have access.
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Jan 27, 2010
I have several installations of my Linq-to-Sql app running in the field. Now I've created a new version, which adds a new column to a certain table. I've added this column in the dbml file. But when updating the installation, I want to preserve the existing database. How to handle this? Linq-to-SQL doesn't seem to like this inconsistency.Is there an easy way to update the existing database using my new dbml file?
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Oct 15, 2011
I have an application that has an Ms Access 2007 DataBase which runns great if access is installed. Is there any code that I can use in vb that I would be able to run access with out installing it.
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Mar 13, 2012
I'm faced with a (fun, actually) data mining problem; I have raw ASCII files from instruments, and I want to move that data (~100 GB) into a database, then be able to run various algorithms determining correlations of time series, etc. I would like to write the mining algorithms in Visual Basic (.net, VS 2010 right now), and be able to do visualizations with VB code I have in hand.On the nature of the data: think of a set of several thousand devices, each recording a measurement at a given interval - so I'm talking time-series vectors.
I spent today re-acquainting myself with VB.NET's interface to (in one case) a Microsoft Access database. What used to be fairly simple - DAO I think it was - involved tables, recordsets, etc (and that would likely be fine). Now I seem to be required to have a weird variety of generally useless objects, e.g. 'adapters', 'datasets', etc. The problem is that I know exactly what I need, and all this extraneous stuff just gets in the way (certainly in coding complexity and opaqueness, and likely in efficiency as well).If any of these mechanisms gave me a kind of virtual access to the entire dataset, and let me control caching parameters, etc.it might be great, but I found nothing along those lines.
Anyway, I tried a number of different approaches, and none seemed at all aimed at what I need to do: efficiently do math on a large dataset. I can't believe I'm the first to have this problem, but I can find no useful wisdom out there. I'd be comfortable with pretty much any underlying database mechanism: MySQL, SQL Server, MS Access, but ideally something generally SQL based (I may eventually have to transition this entire system to draw from a client's SQL database, though that's not an overriding concern now). Other than that I want simplicity and efficiency. I thought my old ODBC techniques would work, and to some extent they do, though modifying tables seemed to have bizarre problems (no errors, but not modifications either).
I do have a fairly aggressive deadline to show some algorithm results, so my focus in the short term is to get something reasonable working *in* the short term - in other words, it's less important to me to pick the 'fastest' relational database than it is to pick a database that lets me focus on coding the algorithms, not working through tedious data access coding. If this db could be any smaller, I'd have tried to do it all 'in memory' at least for proving concepts; I don't want to have to learn an entire jargon and approach just to be able to retrieve data points, and write out new info (e.g., first derivatives of time series).
Perhaps I'll need to bite the bullet and just write something myself, a .dll perhaps just to save and restore large time series vectors. It seems a bit frightening to me that one would have to do this in this age, what with all the database systems out there, but I don't have much time to work through arcane interface logic.
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Oct 1, 2010
what's the best way to handle the updates to the database.For example i have one datagridview that's binded to a datatable (with two fields, id auto incremented and a varchar). The user can do all the operations Insert, Update, Delete.If i insert one row (only the text) and call the update method to save the changes to the database, and after that remove the same row and call the update method the adapter will throw a exception because it didn't update the datatable with the value of the id. So the best way to do this is always calling the fill method after every update?
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Mar 30, 2009
I have two Access database, say database One.mdb and Two.mdb. I want to use VB2005 to export tblCustomer from One.mdb to Two.mdb, and replace the existing tblCustomer in Two.mdb, during run time. I basically want to simulate the export function that is available in MS Access (which can export one table from one Access database to another) with VB2005 during run time. I can think of a way by querying the table to a dataset and then delete everything on the other database before filling the table in that database with the dataset
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Jun 22, 2010
I am trying to import data from an access database to a access database that my project uses I am having problems with combo box fields in the database with the data. I want to import what is displayed instead of the numerical key value. Example: The combo box displays employee names but the value stored is the key value from the employee table so instead of importing John Doe it imports 2 is there a way to make the actual name instead of the number?
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Jul 15, 2009
I am planning to write an application which will be available in 2 versions. one free and the other one paid. The only difference is that in free versions only a maximum of 2 DB entries are allowed. but its unlimited in paid version
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Aug 22, 2010
How to handle the return value of the sql query and store in the database?
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Aug 10, 2009
I am planning to write an application which will be available in 2 versions. one free and the other one paid.The only difference is that in free versions only a maximum of 2 DB entries are allowed. but its unlimited in paid version.DB does not have more than 1 table with 5/6 fields.I am planning to use xml for free version and SQLite for paid version. Is this ok? are there any other options?
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May 29, 2009
using the sql server management studio we can create users to access the database. so we can grant several privileges as well as revoke some. so i want to create a login form with those user's. how to do it. is there any other way [code] in the connection i have to mention the user also.. is it possible. if its possible.
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Feb 16, 2011
I have run into this problem a few times and have never come up with a good answer. I figure others must have dealt with this already.I have a datareader returned from the database and I want to use the values therein however values may or may not contain NULL. I would like to have a unction that takes in the value from the datareader and returns the value if it is not NULL and blank space if it is NULL.The problem I have is that the data-type of the variable I am testing is variable. It can be a String, and Integer or a DateTime. Can anyone suggest a simple way to test the value and then return the original value (as same data-type if possible) or something else if it is NULL
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Apr 18, 2011
I am reading dates from a table in a database to display in a DataGridView column that is formatted as a date. The problem is that when the value is null in the database my program errors out because it cant convert the value to a date. How do you guys handle this? *Edit: If I set the value of my date variable to "Nothing" it displays as "1/1/0001" in my DataGridView, and I would like the cell to be empty for the null dates.
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Mar 22, 2012
I'm trying to handle DBNull exception while reading data from database. It's my code:
...
Dim SQLRDAs SqlDataReader
...
val1= GetStringFromDB(Trim(SQLRD("Name")))
val2= GetStringFromDB(Trim(SQLRD("Level")))
[Code]...
But still I get Conversion from type 'DBNull' to type 'String' is not valid. error.
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Nov 4, 2010
It seems that when using With blocks in VB.NET, the resulting MSIL larger than w/o. So this leads me to ask, are With Blocks really more efficient? MSIL is what gets JITed into native machine code, so smaller code size should imply more efficient code, right?
[Code]...
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May 4, 2010
Where to add this validation, or if there is a more efficient way of doing it and where to put it?
CODE:
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Aug 9, 2009
How to use MVC Pattern efficient?
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Jul 26, 2011
Is there a more efficient way of doing this code?
For Each row As DataRow In dt.Rows
Dim ts1 As String = row(0).ToString
For index As Integer = 1 To 9[code]....
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Aug 26, 2011
just wondering which of these two sort methods would be more efficient movies.OrderBy(Function(m As Movie) m.Title)
[Code]...
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Jan 5, 2010
I need to verify if a certain user exist on my asp.net site.I want to know if which of these two functions is more efficient, faster and better compared to each other and why.
[Code]...
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Aug 1, 2009
I am working on an application that will need to read tons of records (close to 500,000) from one table and insert them into another set of tables in the same database. I though about using SSIS package for this but our DBAs don't want to use that. Now, I am thinking of a multi-threaded approach. I am thinking that I can have a few thread started that will read say (500) records at a time and insert them, then come back and read more.
Now, say I spawn off 3 threads of this application. The first thread reads 500 rows and starts processing them. Can I lock these rows that were already read so that the next thread does not pick them up? I am trying to find some articles regarding this on the internet, but perhaps I am not searching for the correct terms in Google.
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