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  • PreparedStatement

    - by Steel Plume
    Hello, in the case of using PreparedStatement with a single common connection without any pool, can I recreate an instance for every dml/sql operation mantaining the power of prepared statements? I mean: for (int i=0; i<1000; i++) { PreparedStatement preparedStatement = connection.prepareStatement(sql); preparedStatement.setObject(1, someValue); preparedStatement.executeQuery(); preparedStatement.close(); } instead of: PreparedStatement preparedStatement = connection.prepareStatement(sql); for (int i=0; i<1000; i++) { preparedStatement.clearParameters(); preparedStatement.setObject(1, someValue); preparedStatement.executeQuery(); } preparedStatement.close(); my question arises by the fact that I want to put this code into a multithreaded environment, can you give me some advice? thanks

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  • Reusing a PreparedStatement multiple times

    - by Steel Plume
    Hello, in the case of using PreparedStatement with a single common connection without any pool, can I recreate an instance for every dml/sql operation mantaining the power of prepared statements? I mean: for (int i=0; i<1000; i++) { PreparedStatement preparedStatement = connection.prepareStatement(sql); preparedStatement.setObject(1, someValue); preparedStatement.executeQuery(); preparedStatement.close(); } instead of: PreparedStatement preparedStatement = connection.prepareStatement(sql); for (int i=0; i<1000; i++) { preparedStatement.clearParameters(); preparedStatement.setObject(1, someValue); preparedStatement.executeQuery(); } preparedStatement.close(); my question arises by the fact that I want to put this code into a multithreaded environment, can you give me some advice? thanks

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  • Java Prepared Statement arguments!

    - by Epitaph
    I am planning to replace repeatedly executed Statement objects with PreparedStatement objects to improve performance. I am using arguments like the MySQL function now(), and string variables. Most of the PreparedStatement queries I have seen contained constant values (like 10, and strings like "New York") as arguments used for the "?" in the queries. How would I go about using functions like now(), and variables as arguments? Is it necessary to use the "?"s in the queries instead of actual values? I am quite confounded.

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  • Java SQL database independence.

    - by Paul
    Hello, I have been looking for an alternative to Hibernate for various reasons. I came across Liquibase and i like the idea so i am willing to try it. Liquibase will cater for database creation/modification in a SQL independent fashion. My main question is how does my code in my application execute SQL statements without being database dependent? Is there some other project that acts like Hibernates Dialect classes? Thanks, Paul

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  • Using a PreparedStatement to persist an array of Java Enums to an array of Postgres Enums

    - by McGin
    I have a Java Enum: public enum Equipment { Hood, Blinkers, ToungTie, CheekPieces, Visor, EyeShield, None;} and a corresponding Postgres enum: CREATE TYPE equipment AS ENUM ('Hood', 'Blinkers', 'ToungTie', 'CheekPieces', 'Visor', 'EyeShield', 'None'); Within my database I have a table which has a column containing an array of "equipment" items: CREATE TABLE "Entry" ( id bigint NOT NULL DEFAULT nextval('seq'::regclass), "date" character(10) NOT NULL, equipment equipment[] ); And finally when I am running my application I have an array of the "Equipment" enums which I want to persist to the database using a Prepared Statement, and for the life of me I can't figure out how to do it. StringBuffer sb = new StringBuffer("insert into \"Entry\" "); sb.append("( \"date\", \"equipment \" )"); sb.append(" values ( ?, ? )"); PreparedStatement ps = db.prepareStatement(sb.toString()); ps.setString("2010-10-10"); ps.set???????????

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  • Update n number of records using JPA with Optimistic locking

    - by Jacques René Mesrine
    I have a table with a column called "count" and I want to run a cron job that will trigger a statement that performs a SQL like this: update summaryTable set count=4; Note that there might be concurrent threads reading & changing the value for "count" when this cron job is triggered. The table has a version column to support Optimistic Locking. What's an efficient way to update the count in JPA ?

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  • Final form of parametric SQL commands in ADO.NET

    - by mcoolbeth
    I am getting a syntax error when I send a parameterized query to Access from my C# program via ADO.NET. I, of course, know what SQL string I have included in my code, with the parameter names embedded inside. Does anyone know how I can look at the SQL string that is finally sent to the DBMS during after I call cmd.ExecuteNonQuery? Thanks.

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  • MySQL Access denied error

    - by dancingbush
    I am trying to install mySQL on a Mac OS 10.8 and set up a user account. NOTE I am a abs beginner when it comes to using the command line in Terminal window. I used these instructions to install: http://www.macminivault.com/mysql-mountain-lion/ I set my own password for all users here: GRANT ALL ON *.* TO 'root'@'localhost' IDENTIFIED BY 'mypass' WITH GRANT OPTION; quit Every time i try to execute mySQL as a root user on the command line i get this: Ciarans-MacBook-Pro:~ callanmooneys$ mysql -u root ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: NO) I read around on the net and tried various things including tried this to change password: mysqladmin -u root -pyourcurrentmysqlrootpassword password yournewmysqlrootpassword, it returns -> -> USE mysql -> If i simply type 'mysql' and launch the mySQL monitor then try to crete a user account: mysql> USE mysql ERROR 1044 (42000): Access denied for user ''@'localhost' to database 'mysql' mysql> Also tried answers on forum: access is denied for user 'root'@localhost mysql error 1045 returned '[email protected] command not found And MySQL - ERROR 1045 - Access denied: Ciarans-MacBook-Pro:~ callanmooneys$ mysqld_safe --skip-grant-tables 131105 21:44:41 mysqld_safe Logging to '/usr/local/mysql/data/Ciarans-MacBook-Pro.local.err'. 131105 21:44:41 mysqld_safe Starting mysqld daemon with databases from /usr/local/mysql/data /usr/local/mysql/bin/mysqld_safe: line 129: /usr/local/mysql/data/Ciarans-MacBook-Pro.local.err: Permission denied /usr/local/mysql/bin/mysqld_safe: line 166: /usr/local/mysql/data/Ciarans-MacBook-Pro.local.err: Permission denied 131105 21:44:41 mysqld_safe mysqld from pid file /usr/local/mysql/data/Ciarans-MacBook-Pro.local.pid ended /usr/local/mysql/bin/mysqld_safe: line 129: /usr/local/mysql/data/Ciarans-MacBook-Pro.local.err: Permission denied Ciarans-MacBook-Pro:~ callanmooneys$ mysql -u root ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/tmp/mysql.sock' (2) Ciarans-MacBook-Pro:~ callanmooneys$ Feedback appreciated.

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  • How to add an Interbase connection pool to glassfish?

    - by kgrad
    Hi, I am attempting to add an Interbase connection pool to GlassFish v3 to use EJB 3.1 in a project. The glassfish log appears to be connecting to my database properly, it spits out all my table names and indices. However, I get an error INFO: fetching database metadata SEVERE: could not complete schema update java.lang.NullPointerException at interbase.interclient.ResultSet.local_Close(Unknown Source) ... And when I ping the connection pool from within Glassfish I receive "Ping failed Exception - null". I have the following properties set with my connectionpool: resource type: javax.sql.DataSource Datasource Classname: interbase.interclient.DataSource portNumber: 3050 as well as my database info. I can't seem to find information elsewhere. This question is similar but did not receive an answer. thanks.

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  • java.lang.OutOfMemory error when fetching records from Database

    - by Nisarg Mehta
    Hi All, When I try to fetch around 20,000 records and return to ArrayList then it throws java heap space error. JdbcTemplate select = new JdbcTemplate(dataSource); String SQL_SELECT_XML_IRP_ADDRESS = " SELECT * FROM "+ SCHEMA +".XML_ADDRESS "+ " WHERE FILE_NAME = ? "; Object[] parameters=new Object[] {xmlFileName}; return (ArrayList<XmlAddressDto> ) select.query(SQL_SELECT_XML_ADDRESS, parameters,new XmAddressMapExt()); Is there any solution for this ? How should i process this effectively ?

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  • NullPointerException with CallableStatement.getResultSet()

    - by Raj
    Hello, I have a stored proc in SQL Server 2005, which looks like the following (simplified) CREATE PROCEDURE FOO @PARAMS AS BEGIN -- STEP 1: POPULATE tmp_table DECLARE @tmp_table TABLE (...) INSERT INTO @tmp_table SELECT * FROM BAR -- STEP 2: USE @tmp_table FOR FINAL SELECT SELECT abc, pqr FROM BAZ JOIN @tmp_table ON some_criteria END When I run this proc from SQL Server Management Studio, things work fine. However, when I call the same proc from a Java program, using something like: cs = connection.prepareCall("exec proc ?,"); cs.setParam(...); rs = cs.getResultSet(); // BOOM - Null! while(rs.next()) {...} // NPE! I fail to understand why the first result set returned is NULL. Can someone explain this to me? As a workaround, if I check cs.getMoreResults() and if true, try another getResultSet() - THIS time it returns the proper result set. Any pointers please? (I'm using JTDS drivers, if it matters) Thanks, Raj

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  • ClassNotFoundException in MySQL Connector/J

    - by Ephraim
    This has been asked before but I cannot find the answer I need. 1) Using Class.forName("com.mysql.java.Driver") in the eclipse IDE all works well. I load the correct jar (mysql-connector-java-5.1.20-bin.jar), no exception. When I create a jar for my app a1.jar and double click the jar, I get the ClassnotFoundException. I created a .bat file in Windows XP with java -classpath c:\temp\mysql-connector-java-5.1.20-bin.jar -jar c:\temp\a1.jar the app statrs with the same exception. Furthermore using System.getProperty ("java.class.path") shows c:\temp\a1.jar whilst in the IDE I can see several directories

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  • Populate JSP dropdown with database info

    - by Cano63
    I'm looking for the way to populate a JSP dropdown. I want that when the JSP loads it fills the dropdown with the info that I have in a database table. I'm including the code of my class that will create the array and fill it with the database info. What I don't know is how to call that class from my JSP and fill the dropdown. // this will create my array public static ArrayList<DropDownBrands> getBrandsMakes() { ArrayList<DropDownBrands> arrayBrandsMake = new ArrayList<DropDownBrands>(); while (rs.next()) { arrayBrandsMake.add(loadOB(rs)); // CARGO MI ARREGLO CON UN OBJETO } return arrayBrandsMake; } // this will load my array object private static DropDownBrands loadOB(ResultSet rs) throws SQLException { DropDownBrands OB = new DropDownBrands(); OB.setBrands("BRAN"); return OB; }

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  • Auto Reconnect of Database Connection

    - by wesley
    I have a DBCP connection pool in Tomcat. The problem is that when the connection is lost briefly the appliction is broken because DBCP won't try to reconnect again later when there is a connection. Can I get DBCP to reconnect automatically?

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  • Personal project in Java

    - by Chuck
    My first project in java is going to be a program (eventually I have to create a GUI interface but for now CLI would do) to keep track of my books (something similar to what libraries have only a simpler). I need to be able to insert, update, remove, show all books, update, search(by name or author or date). For the design I was thinking one main class Library which will have all of the above as methods that connect to the db and retrieve the data. Is this approach ok? I realize it's simple but it's my first real project and I would appreciate a little feedback. Also, is it too soon to consider reading up on design patterns and database design ?

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  • How to convert String to Java.sql.date and Java.sql.time

    - by Mr Morgan
    Hello If I have a method like this: public static String convertDateTimeToString(DateTime dt) { return dt.getDate() + " " + dt.getTime(); } Which takes a Datetime object of my own which contains a Java.sql.date and a Java.sql.time, what is the best way of reversing the process so that I can substring a Java.sql.date and a Java.sql.time from a string? Or if DateTime dt is a JodaTime DateTime object? If this can be done without reference to Java.util.date. Thanks Mr Morgan.

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  • problem with unicode in javaEE and save question mark in database

    - by Jeus
    when i insert persian information with use JEE6(JSF and JPA) my information save question mark for example "???" === "???" my database is Mysql and my table is UTF-8 . when insert persian data directly in database is correct and save correct. i know that with change one property in JEE my problem go to solved but i don`t know where is it ?

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  • Best way to fetch data from a single database table with multiple threads?

    - by Ravi Bhatt
    Hi, we have a system where we collect data every second on user activity on multiple web sites. we dump that data into a database X (say MS SQL Server). we now need to fetch data from this single table from daatbase X and insert into database Y (say mySql). we want to fetch time based data from database X through multiple threads so that we fetch as fast as we can. Once fetched and stored in database Y, we will delete data from database X. Are there any best practices on this sort of design? any specific things to take care on table design like sharing or something? Are there any other things that we need to take care to make sure we fetch it as fast as we can from threads running on multiple machines? Thanks in advance! Ravi

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  • How to manage a large dataset using Spring MySQL and RowCallbackHandler

    - by rmarimon
    I'm trying to go over each row of a table in MySQL using Spring and a JdbcTemplate. If I'm not mistaken this should be as simple as: JdbcTemplate template = new JdbcTemplate(datasource); template.setFetchSize(1); // template.setFetchSize(Integer.MIN_VALUE) does not work either template.query("SELECT * FROM cdr", new RowCallbackHandler() { public void processRow(ResultSet rs) throws SQLException { System.out.println(rs.getString("src")); } }); I get an OutOfMemoryError because it is trying to read the whole thing. Any ideas?

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  • problem using base64 encoder and InputStreamReader

    - by karoberts
    I have some CLOB columns in a database that I need to put Base64 encoded binary files in. These files can be large, so I need to stream them, I can't read the whole thing in at once. I'm using org.apache.commons.codec.binary.Base64InputStream to do the encoding, and I'm running into a problem. My code is essentially this FileInputStream fis = new FileInputStream(file); Base64InputStream b64is = new Base64InputStream(fis, true, -1, null); InputStreamReader reader = new InputStreamReader(b64is); preparedStatement.setCharacterStream(1, reader); When I run the above code, I get one of these during the execution of the update java.io.IOException: Underlying input stream returned zero bytes, it is thrown deep in the InputStreamReader code. Why would this not work? It seems to me like the reader would attempt to read from the base 64 stream, which would read from the file stream, and everything should be happy.

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  • how to get the result query one by one in jsp and mysql

    - by user261002
    I am trying to implement as Online Mock exam in JSP, but I have a problem to get the questions one by one, it get connceted for the first time, and show me the first question and answers, but when I click on "next" again, it still show me the first question, I think by clicking on "next" it start querying again. please help me. this is my bean : database.SQLSelectStatement sqlselect; database.SQLSelectStatement sqlselect2; static ResultSet questions; static ResultSetMetaData rsm; static ResultSet answers; public void setConnection() throws SQLException { if (database.DatabaseManager.getInstance().connectionOK()) { sqlselect = new database.SQLSelectStatement("question", "question", "0"); sqlselect2 = new database.SQLSelectStatement("answers", "question_id", "0"); questions = sqlselect.executeWithNoCondition(); } } public int i=0; public String getQuestions() throws SQLException { String result = ""; rsm = questions.getMetaData(); for (int i = 0; i < rsm.getColumnCount(); i++) { result += "<th>" + rsm.getColumnName(i + 1) + "</th>"; } if (!questions.isLast()) { questions.next(); System.out.println(i+1); result += "<tr>"; result += "<td>" + questions.getInt(1) + "</td>"; result += "<td>" + questions.getString(2) + "</td>"; result += "</tr>"; result += "<tr>"; sqlselect2.setValue(String.valueOf(questions.getInt(1))); answers = sqlselect2.Execute(); while (answers.next()) { result += "<tr> <td colspan='2'><input type='radio' name='answer' value='" + answers.getString(2) + "'> " + answers.getString(2) + "</td></tr>"; } result += "</tr>"; answers.close(); } return result; } this is the HTML: <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>JSP Page</title> </head> <body> <h1>JSP Page</h1> <jsp:useBean id="exam" class="exam.ExamQuestions"></jsp:useBean> <% exam.setConnection(); %> <form method="post"> <table > <%=exam.getQuestions()%> </table> <input type="submit" name="action" value="next"/> </form> <% String action = request.getParameter("action"); if ("next".equals(action)) { out.println(request.getParameter("answer")); } %> </body> </html>

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