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Thread: Prepared Statement executing but not working. HEADACHE

  1. #1
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    Default Prepared Statement executing but not working. HEADACHE

    Hey guys,

    I cant program my project because this stupid issue has risen out of no where. For some reason the preparedstatement executes but no changes are made in the db. I am using this as a part of a web app i am developing in eclipse but i decided to put this into main and debug this as it wasnt working but its still causing a headache after countless hours on end. Theres no problem with the db connection as theres a similar query that working fine. I have just about tried everything, any help would be appreciated.

     
    public class Main {
    		 static PreparedStatement preparedStatementinsert ;
     
     
    	public static void main(String[] args) {
     
    		try {
    		    Class.forName(DBConstants.DB_DRIVER);
    		} catch (ClassNotFoundException cfe) {		
    			System.out.println("The JDBC drive loading failed.");
    			cfe.printStackTrace();
    		}
    		try {	
    			dbCon = DriverManager.getConnection(DBConstants.DB_NAME);
    		} catch (SQLException se) {
    			SQLExcept.handleException(se);	
    		}
     
    		dbCon=ConnectionManager.getConnection();		
    	String MyQuery= "INSERT INTO LoggedInUsers(Email,SessionID) VALUES(?,?)";
    	String email = "sdas";
    	String Session = "adsadsads";
     
    	try{
     
           preparedStatementinsert= dbCon.prepareStatement(MyQuery);
     
    		preparedStatementinsert.setString(1, "asdddddddddddddddddddddddddemail");
    		preparedStatementinsert.setString(2, "Sessioasdddddddddddddddddddddn");
     
    		int click=preparedStatementinsert.executeUpdate();
    		System.out.println(click);
     
    		}catch(SQLException e){
    			//this.success=false;
    			SQLExcept.handleException(e);
    			e.printStackTrace();
    		}	
     
    	}
    	}

    Variable click keeps on returning 1 every time even if theres a tuple in the relation. Also there has been a few instances(3 out of about a 1000) that the tuple has miraculously appeared in the relation. Doesn't make sense. Also , there are no problems with committing as i have never changed it and its always been at default which is true.


  2. #2
    Administrator copeg's Avatar
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    Default Re: PreparedStatement executing but not working. HEADACHE

    First, your code does not compile - dbCon is not defined: posting an SSCCE always helps break the problem down. Second, dbCon is assigned twice - any reason to assign it twice, and are you sure both assignments point to the same database instance you want it to point to?

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    Default Re: PreparedStatement executing but not working. HEADACHE

    Quote Originally Posted by copeg View Post
    First, your code does not compile - dbCon is not defined: posting an SSCCE always helps break the problem down. Second, dbCon is assigned twice - any reason to assign it twice, and are you sure both assignments point to the same database instance you want it to point to?
    The code does compile, db is is defined in a seperate class. The class is call connection manager and heres the code for that.

     
    public class ConnectionManager {
    	static Connection dbCon;
     
    	public static Connection getConnection()  {
     
    		try {
    		    Class.forName(DBConstants.DB_DRIVER);
    		} catch (ClassNotFoundException cfe) {		
    			System.out.println("The JDBC drive loading failed.");
    			cfe.printStackTrace();
    		}
    		try {	
    			dbCon = DriverManager.getConnection(DBConstants.DB_NAME);
    	//		System.out.print("asasdads");
    		} catch (SQLException se) {
    			SQLExcept.handleException(se);	
    		}
     
    		return dbCon;
     
    	}
    }

    The db constants class just contain the driver name and database file location . The code compiles and runs as i said before otherwise i would be getting a database error. I have simplified the code and it still runs and still does nothing . It is as follows :

  4. #4
    Administrator copeg's Avatar
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    Default Re: PreparedStatement executing but not working. HEADACHE

    The code does compile
    Not for us it doesn't...hence the request for an SSCCE (as well as possibly including the type of database you are working with), with which we can at least see the full code and try and reproduce the behavior. Otherwise, we are left looking at code that looks like it technically should do what you wish (I would recommend closing the PreparedStatement and the Connection - unless they are pooled), but evidently does not.

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    Default Re: PreparedStatement executing but not working. HEADACHE

    Quote Originally Posted by copeg View Post
    Not for us it doesn't...hence the request for an SSCCE (as well as possibly including the type of database you are working with), with which we can at least see the full code and try and reproduce the behavior. Otherwise, we are left looking at code that looks like it technically should do what you wish (I would recommend closing the PreparedStatement and the Connection - unless they are pooled), but evidently does not.
    GUYSSSSS I FIXEDDDDD ITTTTTTT. Apparently if you dont close the dbCon it can cause all sorts of random problems. I have now started closing my db by doing
     
    if (this.dbCon != null) {
    	        try {
    	            this.dbCon.close();
    	        } catch (SQLException e) {}
    	    }
    and its working every time. Any insight to why this might be?

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    Default Re: PreparedStatement executing but not working. HEADACHE

    Unless you close the resources data won't be flushed and hence you were not seeing the changes. Its always best to use finally block if you are prior to JDK 7 or use try with resources statement to cleanup resources instead of a separate try like you have done.

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    Default Re: PreparedStatement executing but not working. HEADACHE

    Hey guys,

    I need some help on fixing my db filepath so i dont have to change it everytime i go onto a new computer. But i am having trouble doing so in eclipse.

    My file tree is like this
     
    Workspace->
                .metadata
                 RemoteSystemTempFiles
                 Servers
                 Myproject->
                                    .settings
                                     build
                                     src ->
                                             package1
                                             package2->
                                                             All my main .java files
                                     WebContent ->
                                             Databases ->
                                                                             MyDB.mdb
                                             Design
                                             Meta-INF
                                             WEB-INF
                                             All my various .jsps
                                     .classpath
                                     .project
     
    I want to know how i can link my MyDB.mdb file in my DB_Name constant, ""jdbc:odbc:Driver={Microsoft Access Driver (*.mdb)};DBQ=C:\\Users\\sup123\\Workspace\\Myproject\\WebContent\\Databases\\MyDB.mdb" ;" such that i dont have to change it everytime i switch computers. I am using an absolute path atm (C:\\workspace etc)
    *
    My project starts from login.jsp which is in the webcontent folder so someone told me that all the files you are referencing to have to be relative to that. Meaning if im specifying my DB file in my DBConstant.java file , it still has to be relative where my login.jsp is in.

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    Default Re: PreparedStatement executing but not working. HEADACHE

    Yes thats right you need to give a relative path.

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    Default Re: PreparedStatement executing but not working. HEADACHE

    ya that was my question but you didnt answer it. How do i give it a relative path?

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    Default Re: PreparedStatement executing but not working. HEADACHE

    Relative path would be Databases/MyDB.mdb.

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    Default Re: PreparedStatement executing but not working. HEADACHE

    doesnt work i tried the following three,
    	public static final String DB_NAME = "jdbc:odbc:Driver={Microsoft Access Driver (*.mdb)};DBQ=\\Databases\\MyDB.mdb" ;
    	public static final String DB_NAME = "jdbc:odbc:Driver={Microsoft Access Driver (*.mdb)};DBQ=.\\Databases\\MyDB.mdb" ;
    	public static final String DB_NAME = "jdbc:odbc:Driver={Microsoft Access Driver (*.mdb)};DBQ=Databases\\MyDB.mdb" ;

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    Default Re: PreparedStatement executing but not working. HEADACHE

    Firstly print the current directory to better understand and give relative path in your app.

  13. #13
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    Default Re: PreparedStatement executing but not working. HEADACHE

    Heres a picture of my directory

    http://imgur.com/33i50on
    Attached Images Attached Images

  14. #14
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    Default Re: PreparedStatement executing but not working. HEADACHE

    Any Ideas for the relative path

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