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  • Best way to run multiple queries per second on database, performance wise?

    - by Michael Joell
    I am currently using Java to insert and update data multiple times per second. Never having used databases with Java, I am not sure what is required, and how to get the best performance. I currently have a method for each type of query I need to do (for example, update a row in a database). I also have a method to create the database connection. Below is my simplified code. public static void addOneForUserInChannel(String channel, String username) throws SQLException { Connection dbConnection = null; PreparedStatement ps = null; String updateSQL = "UPDATE " + channel + "_count SET messages = messages + 1 WHERE username = ?"; try { dbConnection = getDBConnection(); ps = dbConnection.prepareStatement(updateSQL); ps.setString(1, username); ps.executeUpdate(); } catch(SQLException e) { System.out.println(e.getMessage()); } finally { if(ps != null) { ps.close(); } if(dbConnection != null) { dbConnection.close(); } } } And my DB connection private static Connection getDBConnection() { Connection dbConnection = null; try { Class.forName(DB_DRIVER); } catch (ClassNotFoundException e) { System.out.println(e.getMessage()); } try { dbConnection = DriverManager.getConnection(DB_CONNECTION, DB_USER,DB_PASSWORD); return dbConnection; } catch (SQLException e) { System.out.println(e.getMessage()); } return dbConnection; } This seems to be working fine for now, with about 1-2 queries per second, but I am worried that once I expand and it is running many more, I might have some issues. My questions: Is there a way to have a persistent database connection throughout the entire run time of the process? If so, should I do this? Are there any other optimizations that I should do to help with performance? Thanks

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  • How to access web.config connection string in C#?

    - by salvationishere
    I have a 32-bit XP running VS 2008 and I am trying to decrypt my connection string from my web.config file in my C# ASPX file. Even though there are no errors returned, my current connection string doesn't display contents of my selected AdventureWorks stored procedure. I entered it: C:\Program Files\Microsoft Visual Studio 9.0\VC>Aspnet_regiis.exe -pe "connectionStrings" -app "/AddFileToSQL2" Then it said "Succeeded". And my web.config section looks like: <connectionStrings> <add name="Master" connectionString="server=MSSQLSERVER;database=Master; Integrated Security=SSPI" providerName="System.Data.SqlClient" /> <add name="AdventureWorksConnectionString" connectionString="Data Source=SIDEKICK;Initial Catalog=AdventureWorks;Integrated Security=True" providerName="System.Data.SqlClient" /> <add name="AdventureWorksConnectionString2" connectionString="Data Source=SIDEKICK;Initial Catalog=AdventureWorks;Persist Security Info=true; " providerName="System.Data.SqlClient" /> </connectionStrings> And my C# code behind looks like: string connString = ConfigurationManager.ConnectionStrings["AdventureWorksConnectionString2"].ConnectionString; Is there something wrong with the connection string in the web.config or C# code behind file?

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  • How can I tell when a MySQL table was last updated?

    - by RaGE
    In the footer of my page, I would like to add something like "last updated the xx/xx/200x"; with this date being the last time a certain mySQL table has been updated. What is the best way to do that ? Is there a function to retrieve the date ? Should I make an access to the database everytime my footer is displayed ?

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  • Password security; Is this safe?

    - by Camran
    I asked a question yesterday about password safety... I am new at security... I am using a mysql db, and need to store users passwords there. I have been told in answers that hashing and THEN saving the HASHED value of the password is the correct way of doing this. So basically I want to verify with you guys this is correct now. It is a classifieds website, and for each classified the user puts, he has to enter a password so that he/she can remove the classified using that password later on (when product is sold for example). In a file called "put_ad.php" I use the $_POST method to fetch the pass from a form. Then I hash it and put it into a mysql table. Then whenever the users wants to delete the ad, I check the entered password by hashing it and comparing the hashed value of the entered passw against the hashed value in the mysql db, right? BUT, what if I as an admin want to delete a classified, is there a method to "Unhash" the password easily? sha1 is used currently btw. some code is very much appreciated. Thanks

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  • Connecting PHP Server and Android?

    - by user3439988
    I am trying to create a simple test application to transfer data back and forth between my server and Android device. The following are the things I aim for: Ability to upload data and files to the server. To be able to view my files on the server. To be able to download the files from the server to my android device. Ability of the server to send me updates on the files or notifications to my phone. I need a safe and secure way to do these things. I have tried these: HTTPPost requests onto the server and echoing the output accordingly and capturing the HTTPresponse and parsing it. For files I have tried using MultipartEntity, but I think that has been deprecated.

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  • Linq order by aggregate in the select { }

    - by Joe Pitz
    Here is one I am working on: var fStep = from insp in sq.Inspections where insp.TestTimeStamp > dStartTime && insp.TestTimeStamp < dEndTime && insp.Model == "EP" && insp.TestResults != "P" group insp by new { insp.TestResults, insp.FailStep } into grp select new { FailedCount = (grp.Key.TestResults == "F" ? grp.Count() : 0), CancelCount = (grp.Key.TestResults == "C" ? grp.Count() : 0), grp.Key.TestResults, grp.Key.FailStep, PercentFailed = Convert.ToDecimal(1.0 * grp.Count() /tcount*100) } ; I would like to orderby one or more of the fields in the select projection.

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  • Database concurrency issue in .NET application

    - by MC.
    If userA deleted OrderA while userB is modifying OrderA, then userB saves OrderA then there is no order in the database to be updated. My problem is there is no error! The SqlDataAdapter.Update succeeds and returns a "1" indicating a record was modified when this is not true. Does anybody know how this is supposed to work, thanks.

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  • What is this hacker trying to do?

    - by JW
    If you do a search for: http://www.google.co.uk/search?q=0x57414954464F522044454C4159202730303A30303A313527&hl=en&start=30&sa=N you will see a lot of examples of an attempted hack along the lines of: 1) declare @q varchar(8000) select @q = 0x57414954464F522044454C4159202730303A30303A313527 exec(@q) -- What is exactly is it trying to do? Which db is it trying to work on? Do you know of any advisories about this?

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  • Which would be better? Storing/access data in a local text file, or in a database?

    - by TerranRich
    Basically, I'm still working on a puzzle-related website (micro-site really), and I'm making a tool that lets you input a word pattern (e.g. "r??n") and get all the matching words (in this case: rain, rein, ruin, etc.). Should I store the words in local text files (such as words5.txt, which would have a return-delimited list of 5-letter words), or in a database (such as the table Words5, which would again store 5-letter words)? I'm looking at the problem in terms of data retrieval speeds and CPU server load. I could definitely try it both ways and record the times taken for several runs with both methods, but I'd rather hear it from people who might have had experience with this. Which method is generally better overall?

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  • SQL time issue - need it 6 hours forward!

    - by Luke
    My server is currently based on us eastern time, and as I am in the UK, i need to move this forward 6 hours. When using now() in mysql, i am getting the wrong time, is there anything i can add to now() to bring it forward 6 hours? Thanks

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  • How to add user customized data to database?

    - by CSharperWithJava
    I am trying to design a sqlite database that will store notes. Each of these notes will have common fields like title, due date, details, priority, and completed. In addition though, I would like to add data for more specialized notes like price for shopping list items and author/publisher data for books. I also want to have a few general purpose fields that users can fill with whatever text data they want. How can I design my database table in this case? I could just have a field for each piece of data for every note, but that would waste a lot of fields and I'd like to have other options and suggestions.

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  • What should I use to increase performance. View/Query/Temporary Table

    - by Shantanu Gupta
    I want to know the performance of using Views, Temp Tables and Direct Queries Usage in a Stored Procedure. I have a table that gets created every time when a trigger gets fired. I know this trigger will be fired very rare and only once at the time of setup. Now I have to use that created table from triggers at many places for fetching data and I confirms it that no one make any changes in that table. i.e ReadOnly Table. I have to use this tables data along with multiple tables to join and fetch result for further queries say select * from triggertable By Using temp table select ... into #tx from triggertable join t2 join t3 and so on select a,b, c from #tx --do something select d,e,f from #tx ---do somethign --and so on --around 6-7 queries in a row in a stored procedure. By Using Views create view viewname ( select ... from triggertable join t2 join t3 and so on ) select a,b, c from viewname --do something select d,e,f from viewname ---do somethign --and so on --around 6-7 queries in a row in a stored procedure. This View can be used in other places as well. So I will be creating at database rather than at sp By Using Direct Query select a,b, c from select ... into #tx from triggertable join t2 join t3 join ... --do something select a,b, c from select ... into #tx from triggertable join t2 join t3 join ... --do something . . --and so on --around 6-7 queries in a row in a stored procedure. Now I can create a view/temporary table/ directly query usage in all upcoming queries. What would be the best to use in this case.

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  • How to write contents of a rails database to external file

    - by user1296787
    I'm trying to have rails send the contents of my database to an external textfile. I wanted this done everytime a new user is created. However, when i try to do the following in my user.rb model file, before_save :write_data def write_data() File.open("data.txt", "w") do |myfile| myfile.write(User.all) end end It doesn't write the actual contents of the database, instead, it displays something like this User:0x109858540 Can anyone help? Thanks.

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  • Getting highest results in a JOIN

    - by Keithamus
    I've got three tables; Auctions, Auction Bids and Users. The table structure looks something like this: Auctions: id title -- ----- 1 Auction 1 2 Auction 2 Auction Bids: id user_id auction_id bid_amt -- ------- ---------- ------- 1 1 1 200.00 2 2 1 202.00 3 1 2 100.00 Users is just a standard table, with id and user name. My aim is to join these tables so I can get the highest values of these bids, as well as get the usernames related to those bids; so I have a result set like so: auction_id auction_title auctionbid_amt user_username ---------- ------------- -------------- ------------- 1 Auction 1 202.00 Bidder2 2 Auction 2 100.00 Bidder1 So far my query is as follows: SELECT a.id, a.title, ab.bid_points, u.display_name FROM auction a LEFT JOIN auctionbid ab ON a.id = ab.auction_id LEFT JOIN users u ON u.id = ab.user_id GROUP BY a.id This gets the single rows I am after, but it seems to display the lowest bid_amt, not the highest.

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  • Use database dynamically

    - by Redi
    This execution it is giving me an error! Any hints of what am I missing? declare @dbname varchar(500) set @dbname='master' Exec (' Use ' + @dbname + ' go create PROCEDURE [dbo].[krijo_database] @dbname nvarchar(2000), @Direktoria varchar(4000) AS BEGIN declare @stringu nvarchar(100) set @stringu = ''CREATE DATABASE '' + @dbname exec (@stringu) End ')

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  • I insert new parent row and child rowstate changes from Added to unchanged

    - by Joel
    rowsUpdated is an int32 to count how many rows are updated rowsToUpdate = dataset.ParentTable.Select("", "", dataviewRowState.Added) if rowsToUpdate isNot Nothing then for each row as datarow in RowsToUpdate changes the rowstate: rowsUpdated = rowsUpdated + ParentTableAdapter.update(row) Next row End if I'm sure it's something I'm over looking but I just can't see it. Thanks in advance, Joel

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  • Adding Information in SQLite

    - by Cam
    Hi All, I am having trouble with my Android App when adding information into SQLite. I am relatively new to Java/SQLite and though I have followed a lot of tutorials on SQLite and have been able to get the example code to run I am unable to get tables to be created and data to import when running my own app. I have included my code in two Java files Questions (Main Program) and QuestionData (helper class represents the database). Questions.java: public class Questions extends Activity { private QuestionData questions; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.quiztest); questions = new QuestionData(this); try { Cursor cursor = getQuestions(); showQuestions(cursor); } finally { questions.close(); } } private Cursor getQuestions() { //Select Query String loadQuestions = "SELECT * FROM questionlist"; SQLiteDatabase db = questions.getReadableDatabase(); Cursor cursor = db.rawQuery(loadQuestions, null); startManagingCursor(cursor); return cursor; } private void showQuestions(Cursor cursor) { // Collect String Values from Query and Display them this part of the code is wokring fine when there is data present. QuestionData.java public class QuestionData extends SQLiteOpenHelper { private static final String DATABASE_NAME = "TriviaQuiz.db" ; private static final int DATABASE_VERSION = 2; public QuestionData(Context ctx) { super(ctx, DATABASE_NAME, null, DATABASE_VERSION); } @Override public void onCreate(SQLiteDatabase db) { db.execSQL("CREATE TABLE questionlist (_id INTEGER PRIMARY KEY AUTOINCREMENT, QID TEXT, QQuestion TEXT, QAnswer TEXT, QOption1 TEXT, QOption2 TEXT, QOption3 TEXT, QCategoryTagLvl1 TEXT, QCategoryTagLvl2 TEXT, QOptionalTag1 TEXT, QOptionalTag2 TEXT, QOptionalTag3 TEXT, QOptionalTag4 TEXT, QOptionalTag5 TEXT, QTimePeriod TEXT, QDifficultyRating TEXT, QGenderBias TEXT, QAgeBias TEXT, QRegion TEXT, QWikiLink TEXT, QValidationLink1 TEXT, QValidationLink2 TEXT, QHint TEXT, QLastValidation TEXT, QNotes TEXT, QMultimediaType TEXT, QMultimediaLink TEXT, QLastAsked TEXT);"); db.execSQL("INSERT INTO questionlist (_id, QID, QQuestion, QAnswer, QOption1, QOption2, QOption3, QCategoryTagLvl1, QCategoryTagLvl2, QOptionalTag1, QOptionalTag2, QOptionalTag3, QOptionalTag4, QOptionalTag5, QTimePeriod, QDifficultyRating, QGenderBias, QAgeBias, QRegion, QWikiLink, QValidationLink1, QValidationLink2, QHint, QLastValidation, QNotes, QMultimediaType, QMultimediaLink, QLastAsked)"+ "VALUES (null,'Q00001','Example','Ans1','Q1','Q2','Q3','Q4','','','','','','','','','','','','','','','','','','','','')"); } @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME); onCreate(db); } } Any suggestions at all would be great. I have tried debugging which suggests that the database does not exist. Thanks in advance for your assistance.

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  • Mysql query help needed

    - by Me-and-Coding
    Hi, i have two tables category and hotels where category.id should be equal to hotels.catid. Now how do i select 3 rows from each different category from the hotels table. I have this query: select h.* from hotels h inner join category c on h.catid = c.id order by h.catid, h.hid this selects all records, but i want to select three rows per different category so in all it should return 9 rows with 3 rows for each category. If this can not be done in mysql, you could also suggest php code please. Thanks

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