A lock could not obtained within the time requested issue - java

The title is the error I'm getting, when I click load my program freezes. I assume it's because I'm doing a statement inside a statement, but from what I see it's the only solution to my issue. By loading, I want to just repopulate the list of patients, but to do so I need to do their conditions also. The code works, the bottom method is what I'm trying to fix. I think the issue is that I have 2 statements open but I am not sure.
load:
public void DatabaseLoad()
{
try
{
String Name = "Wayne";
String Pass= "Wayne";
String Host = "jdbc:derby://localhost:1527/Patients";
Connection con = DriverManager.getConnection( Host,Name, Pass);
PatientList.clear();
Statement stmt8 = con.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,
ResultSet.CONCUR_UPDATABLE);
String SQL8 = "SELECT * FROM PATIENTS";
ResultSet rs8 = stmt8.executeQuery( SQL8 );
ArrayList<PatientCondition> PatientConditions1 = new ArrayList();
while(rs8.next())
{
PatientConditions1 = LoadPatientConditions();
}
Statement stmt = con.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,
ResultSet.CONCUR_UPDATABLE);
String SQL = "SELECT * FROM PATIENTS";
ResultSet rs = stmt.executeQuery( SQL );
while(rs.next())
{
int id = (rs.getInt("ID"));
String name = (rs.getString("NAME"));
int age = (rs.getInt("AGE"));
String address = (rs.getString("ADDRESS"));
String sex = (rs.getString("SEX"));
String phone = (rs.getString("PHONE"));
Patient p = new Patient(id, name, age, address, sex, phone,
PatientConditions1);
PatientList.add(p);
}
UpdateTable();
UpdateAllViews();
DefaultListModel PatientListModel = new DefaultListModel();
for (Patient s : PatientList) {
PatientListModel.addElement(s.getAccountNumber() + "-" + s.getName());
}
PatientJList.setModel(PatientListModel);
}
catch(SQLException err)
{
System.out.println(err.getMessage());
}
}
This is the method that returns the ArrayList of patient conditions
public ArrayList LoadPatientConditions()
{
ArrayList<PatientCondition> PatientConditionsTemp = new ArrayList();
try
{
String Name = "Wayne";
String Pass= "Wayne";
String Host = "jdbc:derby://localhost:1527/Patients";
Connection con = DriverManager.getConnection( Host,Name, Pass);
Statement stmt = con.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,
ResultSet.CONCUR_UPDATABLE);
String SQL = "SELECT * FROM PATIENTCONDITIONS";
ResultSet rs5 = stmt.executeQuery( SQL );
int e = 0;
while(rs5.next())
{
e++;
String ConName = (rs5.getString("CONDITION"));
PatientCondition k = new PatientCondition(e,ConName);
PatientConditionsTemp.add(k);
}
}
catch(SQLException err)
{
System.out.println(err.getMessage());
}
return PatientConditionsTemp;
}

I had a similar problem.
I was connecting to derby db hosted on local server.
I created 2 simultaneous connections:
With squirrel
With ij tool
When a connection makes a modification on a table, it first gets a lock for the particular table.
This lock is released by the connection only after committing the transaction.
Thus if the second connection tries to read/write the same table, a msg prompts saying:
ERROR 40XL1: A lock could not be obtained within the time requested
To fix this, the connection which modified the table has to commit its transaction.
Hope this helps !

Here is a good place to start: http://wiki.apache.org/db-derby/LockDebugging

You need to close your statement and result set as well so that when you restart your program they won't be open. Add stmt.close(); and rs.close(); at the end of your lines of code within the try and catch statement.

Why could you not use the same connection object to do both the queries?
Like pass that connection object to the LoadPatientConditions() as a parameter and use it there.

Related

How do I use SELECT LAST_INSERT_ID() without closing the connection [duplicate]

I want to INSERT a record in a database (which is Microsoft SQL Server in my case) using JDBC in Java. At the same time, I want to obtain the insert ID. How can I achieve this using JDBC API?
If it is an auto generated key, then you can use Statement#getGeneratedKeys() for this. You need to call it on the same Statement as the one being used for the INSERT. You first need to create the statement using Statement.RETURN_GENERATED_KEYS to notify the JDBC driver to return the keys.
Here's a basic example:
public void create(User user) throws SQLException {
try (
Connection connection = dataSource.getConnection();
PreparedStatement statement = connection.prepareStatement(SQL_INSERT,
Statement.RETURN_GENERATED_KEYS);
) {
statement.setString(1, user.getName());
statement.setString(2, user.getPassword());
statement.setString(3, user.getEmail());
// ...
int affectedRows = statement.executeUpdate();
if (affectedRows == 0) {
throw new SQLException("Creating user failed, no rows affected.");
}
try (ResultSet generatedKeys = statement.getGeneratedKeys()) {
if (generatedKeys.next()) {
user.setId(generatedKeys.getLong(1));
}
else {
throw new SQLException("Creating user failed, no ID obtained.");
}
}
}
}
Note that you're dependent on the JDBC driver as to whether it works. Currently, most of the last versions will work, but if I am correct, Oracle JDBC driver is still somewhat troublesome with this. MySQL and DB2 already supported it for ages. PostgreSQL started to support it not long ago. I can't comment about MSSQL as I've never used it.
For Oracle, you can invoke a CallableStatement with a RETURNING clause or a SELECT CURRVAL(sequencename) (or whatever DB-specific syntax to do so) directly after the INSERT in the same transaction to obtain the last generated key. See also this answer.
Create Generated Column
String generatedColumns[] = { "ID" };
Pass this geneated Column to your statement
PreparedStatement stmtInsert = conn.prepareStatement(insertSQL, generatedColumns);
Use ResultSet object to fetch the GeneratedKeys on Statement
ResultSet rs = stmtInsert.getGeneratedKeys();
if (rs.next()) {
long id = rs.getLong(1);
System.out.println("Inserted ID -" + id); // display inserted record
}
When encountering an 'Unsupported feature' error while using Statement.RETURN_GENERATED_KEYS, try this:
String[] returnId = { "BATCHID" };
String sql = "INSERT INTO BATCH (BATCHNAME) VALUES ('aaaaaaa')";
PreparedStatement statement = connection.prepareStatement(sql, returnId);
int affectedRows = statement.executeUpdate();
if (affectedRows == 0) {
throw new SQLException("Creating user failed, no rows affected.");
}
try (ResultSet rs = statement.getGeneratedKeys()) {
if (rs.next()) {
System.out.println(rs.getInt(1));
}
rs.close();
}
Where BATCHID is the auto generated id.
I'm hitting Microsoft SQL Server 2008 R2 from a single-threaded JDBC-based application and pulling back the last ID without using the RETURN_GENERATED_KEYS property or any PreparedStatement. Looks something like this:
private int insertQueryReturnInt(String SQLQy) {
ResultSet generatedKeys = null;
int generatedKey = -1;
try {
Statement statement = conn.createStatement();
statement.execute(SQLQy);
} catch (Exception e) {
errorDescription = "Failed to insert SQL query: " + SQLQy + "( " + e.toString() + ")";
return -1;
}
try {
generatedKey = Integer.parseInt(readOneValue("SELECT ##IDENTITY"));
} catch (Exception e) {
errorDescription = "Failed to get ID of just-inserted SQL query: " + SQLQy + "( " + e.toString() + ")";
return -1;
}
return generatedKey;
}
This blog post nicely isolates three main SQL Server "last ID" options:
http://msjawahar.wordpress.com/2008/01/25/how-to-find-the-last-identity-value-inserted-in-the-sql-server/ - haven't needed the other two yet.
Instead of a comment, I just want to answer post.
Interface java.sql.PreparedStatement
columnIndexes « You can use prepareStatement function that accepts columnIndexes and SQL statement.
Where columnIndexes allowed constant flags are Statement.RETURN_GENERATED_KEYS1 or Statement.NO_GENERATED_KEYS[2], SQL statement that may contain one or more '?' IN parameter placeholders.
SYNTAX «
Connection.prepareStatement(String sql, int autoGeneratedKeys)
Connection.prepareStatement(String sql, int[] columnIndexes)
Example:
PreparedStatement pstmt =
conn.prepareStatement( insertSQL, Statement.RETURN_GENERATED_KEYS );
columnNames « List out the columnNames like 'id', 'uniqueID', .... in the target table that contain the auto-generated keys that should be returned. The driver will ignore them if the SQL statement is not an INSERT statement.
SYNTAX «
Connection.prepareStatement(String sql, String[] columnNames)
Example:
String columnNames[] = new String[] { "id" };
PreparedStatement pstmt = conn.prepareStatement( insertSQL, columnNames );
Full Example:
public static void insertAutoIncrement_SQL(String UserName, String Language, String Message) {
String DB_URL = "jdbc:mysql://localhost:3306/test", DB_User = "root", DB_Password = "";
String insertSQL = "INSERT INTO `unicodeinfo`( `UserName`, `Language`, `Message`) VALUES (?,?,?)";
//"INSERT INTO `unicodeinfo`(`id`, `UserName`, `Language`, `Message`) VALUES (?,?,?,?)";
int primkey = 0 ;
try {
Class.forName("com.mysql.jdbc.Driver").newInstance();
Connection conn = DriverManager.getConnection(DB_URL, DB_User, DB_Password);
String columnNames[] = new String[] { "id" };
PreparedStatement pstmt = conn.prepareStatement( insertSQL, columnNames );
pstmt.setString(1, UserName );
pstmt.setString(2, Language );
pstmt.setString(3, Message );
if (pstmt.executeUpdate() > 0) {
// Retrieves any auto-generated keys created as a result of executing this Statement object
java.sql.ResultSet generatedKeys = pstmt.getGeneratedKeys();
if ( generatedKeys.next() ) {
primkey = generatedKeys.getInt(1);
}
}
System.out.println("Record updated with id = "+primkey);
} catch (InstantiationException | IllegalAccessException | ClassNotFoundException | SQLException e) {
e.printStackTrace();
}
}
I'm using SQLServer 2008, but I have a development limitation: I cannot use a new driver for it, I have to use "com.microsoft.jdbc.sqlserver.SQLServerDriver" (I cannot use "com.microsoft.sqlserver.jdbc.SQLServerDriver").
That's why the solution conn.prepareStatement(sql, Statement.RETURN_GENERATED_KEYS) threw a java.lang.AbstractMethodError for me.
In this situation, a possible solution I found is the old one suggested by Microsoft:
How To Retrieve ##IDENTITY Value Using JDBC
import java.sql.*;
import java.io.*;
public class IdentitySample
{
public static void main(String args[])
{
try
{
String URL = "jdbc:microsoft:sqlserver://yourServer:1433;databasename=pubs";
String userName = "yourUser";
String password = "yourPassword";
System.out.println( "Trying to connect to: " + URL);
//Register JDBC Driver
Class.forName("com.microsoft.jdbc.sqlserver.SQLServerDriver").newInstance();
//Connect to SQL Server
Connection con = null;
con = DriverManager.getConnection(URL,userName,password);
System.out.println("Successfully connected to server");
//Create statement and Execute using either a stored procecure or batch statement
CallableStatement callstmt = null;
callstmt = con.prepareCall("INSERT INTO myIdentTable (col2) VALUES (?);SELECT ##IDENTITY");
callstmt.setString(1, "testInputBatch");
System.out.println("Batch statement successfully executed");
callstmt.execute();
int iUpdCount = callstmt.getUpdateCount();
boolean bMoreResults = true;
ResultSet rs = null;
int myIdentVal = -1; //to store the ##IDENTITY
//While there are still more results or update counts
//available, continue processing resultsets
while (bMoreResults || iUpdCount!=-1)
{
//NOTE: in order for output parameters to be available,
//all resultsets must be processed
rs = callstmt.getResultSet();
//if rs is not null, we know we can get the results from the SELECT ##IDENTITY
if (rs != null)
{
rs.next();
myIdentVal = rs.getInt(1);
}
//Do something with the results here (not shown)
//get the next resultset, if there is one
//this call also implicitly closes the previously obtained ResultSet
bMoreResults = callstmt.getMoreResults();
iUpdCount = callstmt.getUpdateCount();
}
System.out.println( "##IDENTITY is: " + myIdentVal);
//Close statement and connection
callstmt.close();
con.close();
}
catch (Exception ex)
{
ex.printStackTrace();
}
try
{
System.out.println("Press any key to quit...");
System.in.read();
}
catch (Exception e)
{
}
}
}
This solution worked for me!
I hope this helps!
You can use following java code to get new inserted id.
ps = con.prepareStatement(query, Statement.RETURN_GENERATED_KEYS);
ps.setInt(1, quizid);
ps.setInt(2, userid);
ps.executeUpdate();
ResultSet rs = ps.getGeneratedKeys();
if (rs.next()) {
lastInsertId = rs.getInt(1);
}
It is possible to use it with normal Statement's as well (not just PreparedStatement)
Statement statement = conn.createStatement();
int updateCount = statement.executeUpdate("insert into x...)", Statement.RETURN_GENERATED_KEYS);
try (ResultSet generatedKeys = statement.getGeneratedKeys()) {
if (generatedKeys.next()) {
return generatedKeys.getLong(1);
}
else {
throw new SQLException("Creating failed, no ID obtained.");
}
}
Most others have suggested to use JDBC API for this, but personally, I find it quite painful to do with most drivers. When in fact, you can just use a native T-SQL feature, the OUTPUT clause:
try (
Statement s = c.createStatement();
ResultSet rs = s.executeQuery(
"""
INSERT INTO t (a, b)
OUTPUT id
VALUES (1, 2)
"""
);
) {
while (rs.next())
System.out.println("ID = " + rs.getLong(1));
}
This is the simplest solution for SQL Server as well as a few other SQL dialects (e.g. Firebird, MariaDB, PostgreSQL, where you'd use RETURNING instead of OUTPUT).
I've blogged about this topic more in detail here.
With Hibernate's NativeQuery, you need to return a ResultList instead of a SingleResult, because Hibernate modifies a native query
INSERT INTO bla (a,b) VALUES (2,3) RETURNING id
like
INSERT INTO bla (a,b) VALUES (2,3) RETURNING id LIMIT 1
if you try to get a single result, which causes most databases (at least PostgreSQL) to throw a syntax error. Afterwards, you may fetch the resulting id from the list (which usually contains exactly one item).
In my case ->
ConnectionClass objConnectionClass=new ConnectionClass();
con=objConnectionClass.getDataBaseConnection();
pstmtGetAdd=con.prepareStatement(SQL_INSERT_ADDRESS_QUERY,Statement.RETURN_GENERATED_KEYS);
pstmtGetAdd.setString(1, objRegisterVO.getAddress());
pstmtGetAdd.setInt(2, Integer.parseInt(objRegisterVO.getCityId()));
int addId=pstmtGetAdd.executeUpdate();
if(addId>0)
{
ResultSet rsVal=pstmtGetAdd.getGeneratedKeys();
rsVal.next();
addId=rsVal.getInt(1);
}
If you are using Spring JDBC, you can use Spring's GeneratedKeyHolder class to get the inserted ID.
See this answer...
How to get inserted id using Spring Jdbctemplate.update(String sql, obj...args)
If you are using JDBC (tested with MySQL) and you just want the last inserted ID, there is an easy way to get it. The method I'm using is the following:
public static Integer insert(ConnectionImpl connection, String insertQuery){
Integer lastInsertId = -1;
try{
final PreparedStatement ps = connection.prepareStatement(insertQuery);
ps.executeUpdate(insertQuery);
final com.mysql.jdbc.PreparedStatement psFinal = (com.mysql.jdbc.PreparedStatement) ps;
lastInsertId = (int) psFinal.getLastInsertID();
connection.close();
} catch(SQLException ex){
System.err.println("Error: "+ex);
}
return lastInsertId;
}
Also, (and just in case) the method to get the ConnectionImpl is the following:
public static ConnectionImpl getConnectionImpl(){
ConnectionImpl conexion = null;
final String dbName = "database_name";
final String dbPort = "3306";
final String dbIPAddress = "127.0.0.1";
final String connectionPath = "jdbc:mysql://"+dbIPAddress+":"+dbPort+"/"+dbName+"?autoReconnect=true&useSSL=false";
final String dbUser = "database_user";
final String dbPassword = "database_password";
try{
conexion = (ConnectionImpl) DriverManager.getConnection(connectionPath, dbUser, dbPassword);
}catch(SQLException e){
System.err.println(e);
}
return conexion;
}
Remember to add the connector/J to the project referenced libraries.
In my case, the connector/J version is the 5.1.42. Maybe you will have to apply some changes to the connectionPath if you want to use a more modern version of the connector/J such as with the version 8.0.28.
In the file, remember to import the following resources:
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import com.mysql.jdbc.ConnectionImpl;
Hope this will be helpful.
Connection cn = DriverManager.getConnection("Host","user","pass");
Statement st = cn.createStatement("Ur Requet Sql");
int ret = st.execute();

Unable to execute prepared Statement from DAO

So currently Im trying to do get the auto-incremented primary key by following this answer
Primary key from inserted row jdbc? but apparently the program can't even reach that line and the error appeared on the ps.executeQuery() line after debugging the program, the error it display was only "executeQuery" is not a known variable in the current context. that line, which didn't make sense to me. So how do I go pass this hurdle?
public static int createNewLoginUsers(String newPassword, String newRole) throws SQLException{
Connection conn = DBConnection.getConnection();
Statement st = null;
ResultSet rs = null;
PreparedStatement ps = null;
int id = 0;
try{
String sql = "INSERT into Login(password, role) VALUES(?,?)";
ps = conn.prepareStatement(sql);
ps.setString(1, newPassword);
ps.setString(2, newRole);
ps.executeUpdate();
st = conn.createStatement();
rs = st.executeQuery("SELECT * from Login");
rs.last();
System.out.println(rs.getInt("username"));
id = rs.getInt("username");
rs.close();
} finally{
try{
conn.close();
}catch(SQLException e){
System.out.println(e);
}
}
return id;
}
The part of the method which calls the createNewLoginUsers method
if(newPasstxtfld.getText().equals(retypeNewPasstxtfld.getText())){
//update into database
try {
int username = CreateUsersDAO.createNewLoginUsers( (String) newUserRoleBox.getSelectionModel().getSelectedItem(), newPasstxtfld.getText());
Alert confirmation = new Alert(Alert.AlertType.INFORMATION);
confirmation.setHeaderText("New User Details has been created. Your username is " + username);
confirmation.showAndWait();
} catch (SQLException e) {
}
EDIT:
Databases table added and it's in the provided link below
https://imgur.com/a/Dggp2kc and edit to the codes instead of 2 try blocks in one method i have placed it into a different similar method, updated my codes to the current one I have.

Search for id through database table Java not working

I am trying to understand why I can not search more than one record in a database with Java. It is a Java jsp application but I seems to struggle to figure out where the issue is. I am a beginner with jsp but I am sure would not make any difference
try{
String myDriver = "org.gjt.mm.mysql.Driver";//db driver
String myUrl = database;//connect to db
Class.forName(myDriver);
Connection conn = DriverManager.getConnection(myUrl, user, password);//authenticating on database
String query = "SELECT Cus_ID, Cus_name, Cus_surname, Cus_mail, Cus_Address, Cus_telephone FROM customerdb";//mysql select statement
PreparedStatement sta = conn.prepareStatement(query); //prepared statement
ResultSet rst = sta.executeQuery(query);
while (rst.next())
{
String cusid = rst.getString("Cus_ID"); //variable to retrieve the customer from the database
String cusn = rst.getString("Cus_name");
String cussn = rst.getString("Cus_surname");
String cusm = rst.getString("Cus_mail");
String cusaddr = rst.getString("Cus_Address");
String custel = rst.getString("Cus_telephone");
if(!(customer.equals(cusid))){
request.setAttribute("al", "user not found");
request.getRequestDispatcher("account.jsp").forward(request, response); //and user will stay on login page
}if(customer.equals(cusid)){
System.out.println("hello" + cusid);
request.setAttribute("ID", cusid);
request.setAttribute("name", cusn);
request.setAttribute("surname", cussn);
request.setAttribute("mail", cusm);
request.setAttribute("address", cusaddr);
request.setAttribute("telephone", custel);
request.getRequestDispatcher("account.jsp").forward(request, response);
}else{
}
}
}catch(ClassNotFoundException | SQLException | HeadlessException ex) {
Logger.getLogger(LogInController.class.getName()).log(Level.SEVERE, null, ex);
}
The PreparedStatement#executeQuery() method does not take any parameters. Change this:
ResultSet rst = sta.executeQuery(query);
to this:
ResultSet rst = sta.executeQuery();
This is a somewhat common mistake when using this API. You may have other issues with your code as well, but this should make a noticeable improvement.

Retrieving data from database and increment by one

I am trying to retrieve a data (ID No.) from a database (MySQL) and add it by one. However, when I try to put this code below, when I try to build it, the form doesn't show up. But when I try to remove the Connection cn line, the form with finally show up. I had another project with this code it it worked perfectly fine. I'm not sure why its not working on this one.
public Abstract() throws Exception {
Connection cn = DriverManager.getConnection("jdbc:mysql://localhost:3306/user?zeroDateTimeBehavior=convertToNull","root","");
initComponents();
Statement st = null;
ResultSet rs;
try {
String sql = "SELECT ID from bidding_abstractofprices";
st = cn.prepareStatement(sql);
rs = st.executeQuery(sql);
while(rs.next()){
int id = Integer.parseInt(rs.getString("ID")) + 1;
lblTransacID.setText(String.valueOf(id));
}
}catch (Exception ex){
}
}
What it looks like you are trying to do is to get the ID field value from the last record contained within the bidding_abstractofprices Table contained within your Database and then increment that ID value by one (please correct me if I'm wrong). I don't care why but I can easily assume. Here is how I might do it:
public Abstract() throws Exception {
// Allow all your components to initialize first.
initComponents();
Connection cn = DriverManager.getConnection("jdbc:mysql://localhost:3306/user?zeroDateTimeBehavior=convertToNull","root","");
Statement st = null;
ResultSet rs;
try {
String sql = "SELECT * FROM bidding_abstractofprices ORDER BY ID DESC LIMIT 1;";
st = cn.prepareStatement(sql);
rs = st.executeQuery(sql);
int id = 0;
while(rs.next()){
id = rs.getInt("ID") + 1;
}
lblTransacID.setText(String.valueOf(id));
rs.close();
st.close();
cn.close();
} catch (SQLException ex) {
ex.printStackTrace();
}
}

Java JDBC Incorrect Syntax Error

I have this method to load the objects, however when I am running the sql code it is giving me a Syntax error.
public void loadObjects() {
Statement s = setConnection();
// Add Administrators
try {
ResultSet r = s.executeQuery("SELECT * FROM Administrator;");
while (r.next()) {
Administrator getUser = new Administrator();
getUser.ID = r.getString(2);
ResultSet r2 = s.executeQuery("SELECT * FROM Userx WHERE ID= {" + getUser.ID + "};");
getUser.name = r2.getString(2);
getUser.surname = r2.getString(3);
getUser.PIN = r2.getLong(4);
JBDeveloping.users.administrators.add(getUser);
}
} catch (Exception e) {
System.out.println(e);
}
}
I have tried inserting the curly braces as stated in other questions, but I am either doing it wrong or it doesn't work.
This method should be able to load all administrators but I believe it is only inserting half of the ID.
The ID that it gets, consists of numbers and char; example "26315G"
the Error -
com.microsoft.sqlserver.jdbc.SQLServerException: Incorrect syntax near '26315'.
Edit -
private java.sql.Connection setConnection(){
java.sql.Connection con = null;
try {
Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");
String url = "jdbc:sqlserver://" + host + ";DatabaseName=" + database + ";integratedSecurity=true;";
con = DriverManager.getConnection(url, username, password);
} catch(Exception e) {
System.out.println(e);
}
return con;
}
public void loadObjects() {
java.sql.Connection con = setConnection();
// Add Administrators
try {
PreparedStatement sql = con.prepareStatement("SELECT * FROM Administrator");
ResultSet rs = sql.executeQuery();
while (rs.next()) {
Administrator getUser = new Administrator();
getUser.ID = rs.getString(2);
PreparedStatement sql2 = con.prepareStatement("SELECT * FROM Userx WHERE ID=?");
sql2.setString(1, getUser.ID);
ResultSet r2 = sql2.executeQuery();
getUser.name = r2.getString(2);
getUser.surname = r2.getString(3);
getUser.PIN = r2.getLong(4);
JBDeveloping.users.administrators.add(getUser);
}
} catch (Exception e) {
System.out.println(e);
}
}
Actually it is not the way to do that in JDBC. That way, even if you sort your syntax error, your code is prone to sql injection attacks.
The right way would be:
// Let's say your user id is an integer
PreparedStatement stmt = connection.prepareStatement("select * from userx where id=?");
stmt.setInt(1, getUser.ID);
ResultSet rs = stmt.executeQuery();
This way you are guarded against any attempt to inject SQL in your application request parameters
First of all: if you use concurrently result-sets, you must use separate statements for each one of them (you can not share Statement s between two r and r2). And more, you lack r2.next() before reading from it.
On the other hand: it would be much more effective to use PreparedStatement in the loop that to rewrite the query all the time.
So I'd go for something like this:
public void loadObjects() {
try (
Statement st = getConnection().createStatement();
//- As you read (later) only id, then why to use '*' in this query? It only takes up resources.
ResultSet rs = st.executeQuery("SELECT id FROM Administrator");
PreparedStatement ps = getConnection().prepareStatement("SELECT * FROM Userx WHERE ID = ?");
ResultSet r2 = null;
) {
while (rs.next()) {
Administrator user = new Administrator();
user.ID = rs.getString("id");
ps.setInt(1, user.ID);
r2 = ps.executeQuery();
if (r2.next()) {
user.name = r2.getString(2);
user.surname = r2.getString(3);
user.PIN = r2.getLong(4);
JBDeveloping.users.administrators.add(user);
}
else {
System.out.println("User with ID=" + user.ID + " was not found.");
}
}
}
catch (Exception x) {
x.printStacktrace();
}
}
Please note use of Java7 auto-close feature (you didn't close resources in you code). And last note: until you are not separating statements in your queries, as to JDBC documentation, you should not place ';' at the end of statements (in all cases you shouldn't place ';' as the last character in you query string).
You should not use {} and you should not append parameters into a SQL query like this.
Remove the curly braces and use PreparedStatement instead.
see http://www.unixwiz.net/techtips/sql-injection.html

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