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How to fix the result consisted of more than one row error

I wrote stored procedure in MySQL which looks like this (it works):
DELIMITER //
CREATE PROCEDURE getBrandRows(
IN pBrand VARCHAR(30),
OUT pName VARCHAR(150),
OUT pType VARCHAR(200),
OUT pRetailPrice FLOAT)
BEGIN
SELECT p_name, p_type, p_retailprice INTO pName, pType, pRetailPrice
FROM part
WHERE p_brand LIKE pBrand;
END//
DELIMITER ;
I try to return multiple results and display them. I've tried many ways described here on Stack and in Internet but that does not help me. I have edited my entire code and created a simple one so you can guys paste it and compile. It should work but with error. Here is the code:
package javamysqlstoredprocedures;
import java.sql.CallableStatement;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Types;
public class JavaMySqlStoredProcedures {
private final String DEFAULT_DRIVER = "com.mysql.jdbc.Driver";
private final String DB_URL = "jdbc:mysql://anton869.linuxpl.eu:3306/"
+ "anton869_cars?noAccessToProcedureBodies=true";
private final String DB_USER = "xxx";
private final String DB_PASSWORD = "xxx";
class CallStoredProcedureAndSaveXmlFile extends SwingWorker<Void, Void> {
#Override
public Void doInBackground() {
displaySql();
return null;
}
#Override
public void done() {
}
private void displaySql() {
try {
System.out.println("Connecting to MySQL database...");
Class.forName(DEFAULT_DRIVER);
try (Connection conn = DriverManager.getConnection(DB_URL, DB_USER,
DB_PASSWORD)) {
System.out.println("Connected to MySQL database");
CallableStatement cs = conn.prepareCall("{CALL getBrandRows("
+ "?, ?, ?, ?)}");
cs.setString(1, "Brand#13");
cs.registerOutParameter(2, Types.VARCHAR);
cs.registerOutParameter(3, Types.VARCHAR);
cs.registerOutParameter(4, Types.FLOAT);
boolean results = cs.execute();
while (results) {
ResultSet rs = cs.getResultSet();
while (rs.next()) {
System.out.println("p_name=" + rs.getString("p_name"));
System.out.println("p_type=" + rs.getString("p_type"));
System.out.println("p_retailprice=" + rs
.getFloat("p_retailprice"));
}
rs.close();
results = cs.getMoreResults();
}
cs.close();
} catch (SQLException e) {
e.printStackTrace();
}
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
}
}
public JavaMySqlStoredProcedures() {
new CallStoredProcedureAndSaveXmlFile().execute();
}
public static void main(String[] args) {
JavaMySqlStoredProcedures jmssp = new JavaMySqlStoredProcedures();
}
}

ResultSet can handle multiple records.I found some errors in your code.Try these steps
Move your all close method to finally block.
try {
//do something
} catch (Exception e) {
//do something
} finally {
try{
resultSet.close();
statement.close();
connection.close();
} catch (SQLException se) {
//do something
}
}
You can put your result into List. See sample
List<YourObject> list = new ArrayList<YourObject>();
while (rs.next()) {
YourObject obj = new Your Object();
obj.setName(rs.getString("p_name"));
obj.setType(rs.getString("p_type"));
obj.setRetailPrice(rs.getFloat("p_retailprice"));
list.add(obj);
}
Make sure your query is correct and database connection is Ok.

Don't use IN or OUT parameter if you just simply want to display result. And also you should add '%%' in your LIKE clause with the help of CONCAT function. Please try this one:
DELIMITER //
CREATE PROCEDURE getBrandRows(
pBrand VARCHAR(30)
)
BEGIN
SELECT p_name, p_type, p_retailprice INTO pName, pType, pRetailPrice
FROM part
WHERE p_brand LIKE CONCAT("%", pBrand, "%");
END//
DELIMITER ;

I am posting correct solution to everybody who have smiliar problem:
1. Corrected Stored Procedure:
DELIMITER //
CREATE PROCEDURE getBrandRows(
IN pBrand VARCHAR(30))
BEGIN
SELECT p_name, p_type, p_retailprice
FROM part
WHERE p_brand = pBrand;
END//
DELIMITER ;
2. Corrected Java code:
package javamysqlstoredprocedures;
import java.sql.CallableStatement;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Types;
public class JavaMySqlStoredProcedures {
private final String DEFAULT_DRIVER = "com.mysql.jdbc.Driver";
private final String DB_URL = "jdbc:mysql://anton869.linuxpl.eu:3306/"
+ "anton869_cars?noAccessToProcedureBodies=true";
private final String DB_USER = "xxx";
private final String DB_PASSWORD = "xxx";
class CallStoredProcedureAndSaveXmlFile extends SwingWorker<Void, Void> {
#Override
public Void doInBackground() {
displaySql();
return null;
}
#Override
public void done() {
}
private void displaySql() {
Connection conn = null;
CallableStatement cs = null;
ResultSet rs = null;
try {
System.out.println("Connecting to MySQL database...");
Class.forName(DEFAULT_DRIVER);
conn = DriverManager.getConnection(DB_URL, DB_USER,
DB_PASSWORD);
System.out.println("Connected to MySQL database");
cs = conn.prepareCall("{CALL getBrandRows(?)}");
cs.setString(1, "Brand#13");
boolean results = cs.execute();
while (results) {
rs = cs.getResultSet();
while (rs.next()) {
System.out.println("p_name=" + rs.getString("p_name"));
System.out.println("p_type=" + rs.getString("p_type"));
System.out.println("p_retailprice=" + rs.getFloat(
"p_retailprice"));
}
results = cs.getMoreResults();
}
} catch (SQLException | ClassNotFoundException e) {
} finally {
try {
if (rs != null ) rs.close();
if (cs != null) cs.close();
if (conn != null) conn.close();
} catch (SQLException e) {
}
}
}
public JavaMySqlStoredProcedures() {
new CallStoredProcedureAndSaveXmlFile().execute();
}
public static void main(String[] args) {
JavaMySqlStoredProcedures jmssp = new JavaMySqlStoredProcedures();
}
}

Your stored procedure returns more than one row. Just correct logic behind your select query inside the stored procedure it should return only one row.
here how to return multiple value

Inserting data into a database - org.h2.jdbc.JdbcSQLException: Column count does not match; SQL statement:

I've been trying to save values into a database called "CLIENT".
The database is created via this code:
package Database;
//STEP 1. Import required packages
import java.sql.*;
public class JDBCExampleCreateTables {
// JDBC driver name and database URL
private static String JDBC_DRIVER = "org.h2.Driver";
private static String DB_URL = "jdbc:h2:file:C:/WAKILI/WAKILIdb";
// Database credentials
private static String USER = "sa";
private static String PASS = "";
public static void main (String[] args) {
Connection conn = null;
Statement stmt = null;
try {
//STEP 2: Register JDBC driver
Class.forName(JDBC_DRIVER);
//STEP 3: Open a connection
System.out.println("Connecting to a selected database...");
conn = DriverManager.getConnection(DB_URL, USER, PASS);
System.out.println("Connected database successfully...");
//STEP 4: Execute a query
System.out.println("Creating table in given database...");
stmt = conn.createStatement();
String sql = "CREATE TABLE CLIENT " +
"(ID INT UNSIGNED NOT NULL AUTO_INCREMENT, " +
" fullNames VARCHAR(255), " +
" iDNumber VARCHAR(255), " +
" pINNumber VARCHAR(255), " +
" passportNumber VARCHAR(255), " +
" postOfficeBoxNumber VARCHAR(255), " +
" postalCode VARCHAR(255), " +
" telephoneNumberLandline VARCHAR(255), " +
" telephoneNumberMobile VARCHAR(255), " +
" CARD VARCHAR(255)) ";
stmt.executeUpdate(sql);
System.out.println("Created table in given database...");
} catch (SQLException se) {
//Handle errors for JDBC
se.printStackTrace();
} catch (Exception e) {
// Handle errors for Class.forName
e.printStackTrace();
} finally {
// finally block used to close resources
try {
if (stmt!=null)
conn.close();
} catch(SQLException se) {
} // do nothing
try {
if (conn!=null)
conn.close();
} catch (SQLException se) {
se.printStackTrace();
} // end finally try
} // end try
System.out.println("Goodbye!");
} // end main
} // end
The class that I'm trying to have save into the database is:
package Database;
//STEP 1. Import required packages
import java.sql.*;
public class JDBCExampleInsertRecords {
public final String values;
public final String table;
public JDBCExampleInsertRecords (String values, String table)
{
this.values = values;
this.table = table;
}
// JDBC driver name and database URL
private static String JDBC_DRIVER = "org.h2.Driver";
private static String DB_URL = "jdbc:h2:file:C:/WAKILI/WAKILIdb";
// Database credentials
private static String USER = "sa";
private static String PASS = "";
public static void main () {
Connection conn = null;
Statement stmt = null;
try {
//STEP 2: Register JDBC driver
Class.forName(getJDBC_DRIVER());
//STEP 3: Open a connection
System.out.println("Connecting to a selected database...");
conn = DriverManager.getConnection(getDB_URL(), getUSER(), getPASS());
System.out.println("Connected database successfully...");
//STEP 4: Execute a query
System.out.println("Inserting records into the table...");
stmt = conn.createStatement();
String sql = "INSERT INTO CLIENT " + "VALUES ((values))";
stmt.executeUpdate(sql);
System.out.println("Inserted records into the table...");
} catch (SQLException se) {
//Handle errors for JDBC
se.printStackTrace();
} catch (Exception e) {
//Handle errors for Class.forName
e.printStackTrace();
} finally {
//finally block used to close resources
try {
if (stmt != null)
conn.close();
} catch (SQLException se) {
} // do nothing
try {
if (conn!=null)
conn.close();
} catch (SQLException se) {
se.printStackTrace();
} //end finally try
} //end try
System.out.println("Goodbye!");
} //end main
/**
* #return the JDBC_DRIVER
*/
public static String getJDBC_DRIVER() {
return JDBC_DRIVER;
}
/**
* #param aJDBC_DRIVER the JDBC_DRIVER to set
*/
public static void setJDBC_DRIVER(String aJDBC_DRIVER) {
JDBC_DRIVER = aJDBC_DRIVER;
}
/**
* #return the DB_URL
*/
public static String getDB_URL() {
return DB_URL;
}
/**
* #param aDB_URL the DB_URL to set
*/
public static void setDB_URL(String aDB_URL) {
DB_URL = aDB_URL;
}
/**
* #return the USER
*/
public static String getUSER() {
return USER;
}
/**
* #param aUSER the USER to set
*/
public static void setUSER(String aUSER) {
USER = aUSER;
}
/**
* #return the PASS
*/
public static String getPASS() {
return PASS;
}
/**
* #param aPASS the PASS to set
*/
public static void setPASS(String aPASS) {
PASS = aPASS;
}
} //end
The code that gets the values is in a Class called "AddNewClient" and is as follows:
public String getValues () {
String fullNames = fullNamesJTextField.getText();
String iDNumber = identificationNumberJTextField.getText();
String pINNumber = pINNumberJTextField.getText();
String passportNumber = passportNumberJTextField.getText();
String postOfficeBoxNumber = postOfficeBoxNumberJTextField.getText();
String postalCode = postalCodeJTextField.getText();
String telephoneNumberLandline = telephoneNumberLandlineJTextField.getText();
String telephoneNumberMobile = telephoneNumberMobileJTextField.getText();
List<String> client = new ArrayList<String>();
client.add(fullNames);
client.add(iDNumber);
client.add(pINNumber);
client.add(passportNumber);
client.add(postOfficeBoxNumber);
client.add(postalCode);
client.add(telephoneNumberLandline);
client.add(telephoneNumberMobile);
StringBuilder builder = new StringBuilder();
String listStringClient = "";
for (String s : client)
{
listStringClient += "NULL" + "'" + s + "'" + ",";
}
return listStringClient;
}
I get an error message:
run:
Connecting to a selected database...
Connected database successfully...
Inserting records into the table...
org.h2.jdbc.JdbcSQLException: Column count does not match; SQL statement:
I've been at this for the past two days to no success whatsoever. I will be very, very very greatful to anyone who would come to my rescue. Thank you.

This is where one problem is:
String sql = "INSERT INTO CLIENT " + "VALUES ((values))";
stmt.executeUpdate(sql);
Values should be the getValues() method, instead of just a string, so
String sql = "INSERT INTO CLIENT VALUES (" + getValues() + ")";
Additionally, since you do not specify which columns, it is assumed that all columns are being entered in the values. If CARD does not have a default value in your SQL database, and if it cannot be NULL, you're going to have a problem.
Finally, this is a little strange:
for (String s : client)
{
listStringClient += "NULL" + "'" + s + "'" + ",";
}
You'll want the values, not 'NULL', so it should be
for (String s : client)
{
listStringClient += "'" + s + "'" + ",";
}
And finally, the way you're doing it, you're going to have an extra comma at the end (ex: 'value1','value2','value3',)
Clip the final comma:
return listStringClient.substring(0, listStringClient.size() - 1);
Granted, there's a better way to do the for loop where you do not have that extra comma.
End the end, the sql String should look like this:
"INSERT INTO CLIENT VALUES('value1','value2','value3','value4','value5','value6')"
Do a System.out.println(sql) and see what the String statement is that you're trying to execute. You'll see the error then.
Here's a better way to build your values string without the comma issue:
Iterator<String> iter = client.iterator();
StringBuilder sb = new StringBuilder();
while (iter.hasNext()) {
sb.append("'").append(iter.next()).append("'");
if (iter.hasNext())
sb.append(",");
}
return sb.toString();

You forget to mention the value for CARD column. If you dont want to set any value there, just pass ' '.
Your for loop should be like this
for (String s : client)
{
listStringClient += "NULL" + "'" + s + "'" + ",";//GIVES YOU ERROR BECAUSE AT THE END OF
} // FOR LOOP IT HAS , IN THE END OF STRING.
listStringClient+="' '";//This is for CARD COLUMN.

You do not pass any value in your statement. Following code is static, it does not have parameters:
INSERT INTO CLIENT " + "VALUES ((values))
It is nonsense SQL command: INSERT INTO CLIENT VALUES ((values)). You wanted express
String sql = "INSERT INTO CLIENT VALUES " + getValues()";
I prefer to use PreparedStatement, as it is safe and it will escape dangerous characters:
String sql = "INSERT INTO PRODUCT VALUES(?,?,?,?,?,?,?,?,?,?)";
PreparedStatement prest = con.prepareStatement(sql);
prest.setString(1, "asdf");
prest.setInt(2, 2009);
// etc
int count = prest.executeUpdate();

I think instead of :
String sql = "INSERT INTO CLIENT " + "VALUES ((values))";
You want something like :
String sql = "INSERT INTO CLIENT " + "VALUES ("+getValues()+")";
Also the implementation of getValues is kind of strange :
for (String s : client)
{
listStringClient += "NULL" + "'" + s + "'" + ",";
}
Probably it could be :
for (String s : client)
{
listStringClient += "'" + s + "',"
}
listStringClient += "NULL";

I can't thank you all enough for the amazing answers. I put the various ideas and came up with this solution to my problem.
My working answer to my Question above takes ideas from Leos Literak, abmitchell, Vimal Bera and Grisha's answers.
The database is created via this code:
package Database;
//STEP 1. Import required packages
import java.sql.*;
public class JDBCExampleCreateTables {
// JDBC driver name and database URL
private static String JDBC_DRIVER = "org.h2.Driver";
private static String DB_URL = "jdbc:h2:file:C:/WAKILI/WAKILIdb";
// Database credentials
private static String USER = "sa";
private static String PASS = "";
public static void main (String[] args) {
Connection conn = null;
Statement stmt = null;
try {
//STEP 2: Register JDBC driver
Class.forName(JDBC_DRIVER);
//STEP 3: Open a connection
System.out.println("Connecting to a selected database...");
conn = DriverManager.getConnection(DB_URL, USER, PASS);
System.out.println("Connected database successfully...");
//STEP 4: Execute a query
System.out.println("Creating table in given database...");
stmt = conn.createStatement();
String sql = "CREATE TABLE CLIENT " +
"(ID INT UNSIGNED NOT NULL AUTO_INCREMENT, " +
" fullNames VARCHAR(255), " +
" iDNumber VARCHAR(255), " +
" pINNumber VARCHAR(255), " +
" passportNumber VARCHAR(255), " +
" postOfficeBoxNumber VARCHAR(255), " +
" postalCode VARCHAR(255), " +
" telephoneNumberLandline VARCHAR(255), " +
" telephoneNumberMobile VARCHAR(255)) ";
stmt.executeUpdate(sql);
System.out.println("Created table in given database...");
} catch (SQLException se) {
//Handle errors for JDBC
se.printStackTrace();
} catch (Exception e) {
// Handle errors for Class.forName
e.printStackTrace();
} finally {
// finally block used to close resources
try {
if (stmt!=null)
conn.close();
} catch(SQLException se) {
} // do nothing
try {
if (conn!=null)
conn.close();
} catch (SQLException se) {
se.printStackTrace();
} // end finally try
} // end try
System.out.println("Goodbye!");
} // end main
} // end
The class that saves into the database is:
package Database;
//STEP 1. Import required packages
import java.sql.*;
public class JDBCExampleInsertRecords {
public static String values;
public final String table;
public JDBCExampleInsertRecords (String values, String table)
{
this.values = values;
this.table = table;
}
// JDBC driver name and database URL
private static String JDBC_DRIVER = "org.h2.Driver";
private static String DB_URL = "jdbc:h2:file:C:/WAKILI/WAKILIdb";
// Database credentials
private static String USER = "sa";
private static String PASS = "";
public static void main () {
Connection conn = null;
Statement stmt = null;
try {
//STEP 2: Register JDBC driver
Class.forName(getJDBC_DRIVER());
//STEP 3: Open a connection
System.out.println("Connecting to a selected database...");
conn = DriverManager.getConnection(getDB_URL(), getUSER(), getPASS());
System.out.println("Connected database successfully...");
//STEP 4: Execute a query
System.out.println("Inserting records into the table...");
stmt = conn.createStatement();
String sql = "INSERT INTO CLIENT VALUES (NULL, " + (values) + ")";
stmt.executeUpdate(sql);
System.out.println("Inserted records into the table...");
} catch (SQLException se) {
//Handle errors for JDBC
se.printStackTrace();
} catch (Exception e) {
//Handle errors for Class.forName
e.printStackTrace();
} finally {
//finally block used to close resources
try {
if (stmt != null)
conn.close();
} catch (SQLException se) {
} // do nothing
try {
if (conn!=null)
conn.close();
} catch (SQLException se) {
se.printStackTrace();
} //end finally try
} //end try
System.out.println("Goodbye!");
} //end main
/**
* #return the JDBC_DRIVER
*/
public static String getJDBC_DRIVER() {
return JDBC_DRIVER;
}
/**
* #param aJDBC_DRIVER the JDBC_DRIVER to set
*/
public static void setJDBC_DRIVER(String aJDBC_DRIVER) {
JDBC_DRIVER = aJDBC_DRIVER;
}
/**
* #return the DB_URL
*/
public static String getDB_URL() {
return DB_URL;
}
/**
* #param aDB_URL the DB_URL to set
*/
public static void setDB_URL(String aDB_URL) {
DB_URL = aDB_URL;
}
/**
* #return the USER
*/
public static String getUSER() {
return USER;
}
/**
* #param aUSER the USER to set
*/
public static void setUSER(String aUSER) {
USER = aUSER;
}
/**
* #return the PASS
*/
public static String getPASS() {
return PASS;
}
/**
* #param aPASS the PASS to set
*/
public static void setPASS(String aPASS) {
PASS = aPASS;
}
} //end
The code that gets the values is in a Class called "AddNewClient" and is as follows:
public String getValues () {
String fullNames = fullNamesJTextField.getText();
String iDNumber = identificationNumberJTextField.getText();
String pINNumber = pINNumberJTextField.getText();
String passportNumber = passportNumberJTextField.getText();
String postOfficeBoxNumber = postOfficeBoxNumberJTextField.getText();
String postalCode = postalCodeJTextField.getText();
String telephoneNumberLandline = telephoneNumberLandlineJTextField.getText();
String telephoneNumberMobile = telephoneNumberMobileJTextField.getText();
List<String> client = new ArrayList<String>();
client.add(fullNames);
client.add(iDNumber);
client.add(pINNumber);
client.add(passportNumber);
client.add(postOfficeBoxNumber);
client.add(postalCode);
client.add(telephoneNumberLandline);
client.add(telephoneNumberMobile);
Iterator<String> iter = client.iterator();
StringBuilder sb = new StringBuilder();
while (iter.hasNext()) {
sb.append("'").append(iter.next()).append("'");
if (iter.hasNext())
sb.append(",");
}
return sb.toString();
}

can we create a common database class in java

i want to know if we can create a common database class same like we create a connection class and just call getConnection when we need connection to be established.
Basically, i want a database manager class which can handle database operation irrespective of tablename, columncount,etc.
tablename, columnname, values to be inserted would be passed as parameters from servlet.
that way, i can reduce duplication of code. m tryin to make a simple mvc application using jsp-servlets. my database is mysql. i dont know struts, spring, hibernate.
For Example, servlet code will call(databaseManager is the class name.) :
int count=databaseManager.getCount("tableName", "columnName", "value");
and in databaseManager, there will be a function -
public static int getCount(String tableName, String[] arrC, objectArray[] arrV)
{}
similarly, for other functions.
i googled and found out that it could be done using metadata.
but i dont know how to use it.
it would be helpful if u could post code of one function for similar approach.

Check DbUtils component of Apache Commons. Also there are examples provided.

Yes, sure you can. I have done something similar (but not the same) and there can be many approaches. I think you should google more, I'm sure, that there are lot of open source applications for database management/database clients. Try to get inspiration there.
Okay, here is some code for inspiration. It is not totally generic, or what are you looking for, but I think, this could lead you somewhere. If not, throw the stone. :-)
Database provider class:
import java.lang.reflect.Constructor;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
import org.apache.commons.beanutils.BeanUtils;
import org.apache.commons.beanutils.DynaProperty;
public class DatabaseProvider<T extends DatabaseObject> {
private static DatabaseProvider databaseProvider;
private static String connectionString = "";
private static String password = "";
private static String username = "";
private static boolean initialized = true;
public DatabaseProvider(){ }
public static void initDatabaseProvider() {
try {
DriverManager.registerDriver(new oracle.jdbc.driver.OracleDriver());
}
catch(SQLException e){
initialized = false;
e.printStackTrace();
}
connectionString = "XXX";
username = "XXX";
password = "XXX";
}
public List<T> performSimpleSelectQuery(String table, String columns, String where, Class targetObj) throws SQLException {
if(!initialized) return null;
List<T> results = new ArrayList<T>();
Constructor ct;
DatabaseObject dbo;
try {
ct = targetObj.getConstructor(null);
dbo = (DatabaseObject)ct.newInstance(null);
}
catch(Exception e){
e.printStackTrace();
return null;
}
String[] cols = columns.split(",");
String[] properties = new String[cols.length];
for(int i = 0; i < cols.length; i++){
cols[i] = cols[i].trim();
properties[i] = dbo.getMappingFromColumnName(cols[i]);
}
Connection conn = DriverManager.getConnection(connectionString, username, password);
PreparedStatement pst = conn.prepareStatement("SELECT " + columns + " FROM " + table + (where.equals("") ? "" : " WHERE " + where));
pst.execute();
ResultSet rs = pst.getResultSet();
while(rs.next()){
try {
dbo = (DatabaseObject)ct.newInstance(null);
for(int i = 0; i < cols.length; i++){
BeanUtils.setProperty(dbo, properties[i], rs.getObject(cols[i]));
}
results.add((T)dbo);
}
catch(Exception e){
e.printStackTrace();
rs.close();
pst.close();
conn.close();
return null;
}
}
rs.close();
pst.close();
conn.close();
return results;
}
public int performInsert(String columns, String values, String table) throws SQLException {
String sqlInsert = "INSERT INTO " + table + " (" + columns + ") VALUES (" + values + ")";
Connection conn = DriverManager.getConnection(connectionString, username, password);
PreparedStatement pst = conn.prepareStatement(sqlInsert);
int toReturn = 0;
try {
toReturn = pst.executeUpdate();
}
catch(Exception e){
e.printStackTrace();
pst.close();
conn.close();
return toReturn;
}
pst.close();
conn.close();
return toReturn;
}
}
Database object class:
import java.util.HashMap;
public abstract class DatabaseObject {
protected HashMap<String, String> dbToBeanMapping = new HashMap<String, String>();
public DatabaseObject() {
initialize();
}
protected abstract void initialize();
public String getMappingFromColumnName(String columnName) {
return dbToBeanMapping.get(columnName);
}
}
Example class:
public class CounterParty extends DatabaseObject {
private String name;
private int instrument;
private int partyId;
public int getPartyId() {
return partyId;
}
public void setPartyId(int partyId) {
this.partyId = partyId;
}
public CounterParty(){}
public int getInstrument() {
return instrument;
}
public void setInstrument(int instrument) {
this.instrument = instrument;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
protected void initialize() {
this.dbToBeanMapping.put("company_name", "name");
this.dbToBeanMapping.put("party_id", "partyId");
this.dbToBeanMapping.put("inst_id", "instrument");
}
}

NullPointerException when using executeQuery

I have a null pointer exception in
ResultSet rs = aStatement.executeQuery(Query); // it can't be executed
my code is like this :
public static boolean testLogin(String user, String password) throws SQLException {
String Query = "select * from TBL_Users where userName = '" + user + "' and passWord = '" + password + "' ";
ResultSet rs = aStatement.executeQuery(Query);
while (rs.next()) {
info.Id = rs.getInt("ID");
info.userName = rs.getString("userName");
info.Name = rs.getString("User_Name");
info.Password = rs.getString("passWord");
info.isAdmin = rs.getBoolean("Admin");
return true;
}
return false;
}
}

Most likely aStatement is null.

Sounds like you think aStatement should not be null, but it is.
This is bad JDBC code, for many reasons:
No cleanup of resources.
Doesn't use PreparedStatement
Keeps creating the query string over and over again instead of using a static variable
Doesn't follow Java coding standards ("Query" should be "query")
Here's another way to write it. Start with an interface:
package persistence;
import java.sql.SQLException;
public interface CredentialDao
{
boolean isValidUser(String username, String password) throws SQLException;
}
Write an implementation:
package persistence;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
public class CredentialDaoImpl implements CredentialDao
{
private static final String CREDENTIAL_QUERY = "SELECT COUNT() FROM USER WHERE USERNAME = ? AND PASSWORD = ?";
private Connection connection;
public CredentialDaoImpl(Connection connection)
{
this.connection = connection;
}
public boolean isValidUser(String username, String password) throws SQLException
{
boolean isValidUser = false;
PreparedStatement ps = null;
ResultSet rs = null;
try
{
ps = this.connection.prepareStatement(CREDENTIAL_QUERY);
ps.setString(1, username);
ps.setString(2, password);
rs = ps.executeQuery();
while (rs.next())
{
int count = rs.getInt(1);
isValidUser = (count > 0);
}
}
finally
{
DatabaseUtils.close(rs);
DatabaseUtils.close(ps);
}
return isValidUser;
}
}

The aStatement variable is apparently null, please validate that it is correctly set. You should consider read the Java Naming Conventions and make sure you use the lower camel case for variables and java bean conventions.
For code snippets in stackoverflow if they are not self-explanatory, you should obey the rules of the SSCCE, this will help you to get more and better answers. Also you should provide a stack trace with the occured exception.

Use prepared statements.
Connection con = ...; // obtain connection here
PreparedStatement pstmt = con.prepareStatement("select * from TBL_Users where userName = ?'");
pstmt.setInt(1, userName);
ResultSet rs = pstmt .executeQuery();
...
// do clean up here

while (rs.next()) {
info.Id = rs.getInt("ID");
info.userName = rs.getString("userName");
info.Name = rs.getString("User_Name");
info.Password = rs.getString("passWord");
info.isAdmin = rs.getBoolean("Admin");
return true; // Huh? What?
}
What is info refering to and why is there a return imediatly after the assignments?

Why is java.sql.DriverManager.getConnection(...) hanging?

I am attempting to get a connection to my University's MySQL DB but the connection is hanging.
import java.sql.*;
public class ConnectToDB {
public static void main(String args[]){
try {
Class.forName("com.mysql.jdbc.Driver").newInstance();
String url = "jdbc:mysql://db.cs.myUniversity.com/dbName";
System.out.println("BEFORE");
Connection con = DriverManager.getConnection(url,"me", "password");
System.out.println("AFTER");
...
This call: time java ConnectToDB prints (after I eventually kill it):
Copyright 2004, R.G.Baldwin
BEFORE
AFTER
real 3m9.343s
user 0m0.316s
sys 0m0.027s
I just downloaded MySQL Connector/J from here. I am not sure if that is part of the problem. I followed the directions fairly precisely.
I can also connect to mysql on the command line like this:
$ mysql -u me -h db.cs.myUniversity.com -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 882328
Server version: 5.0.77 Source distribution
Type 'help;' or '\h' for help. Type '\c' to clear the buffer.
mysql> use dbName;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A
Database changed
mysql> SHOW tables;
+-------------------+
| Tables_in_dbName |
+-------------------+
| classics |
+-------------------+
1 row in set (0.00 sec)
Possible Problems:
The Java code I wrote
How I installed MySQL Connector/J
Some kind of network problem blocking the connection
Question: What should I do to solve this problem? Why is the getConnection call hanging?
I was following this tutorial

The output you provide is not helpful.
I see BEFORE and AFTER being printed, so the connection was made. The code doesn't show what those timings encompass, so I can't tell what they mean.
If you're suggesting that your code had to killed because the connection was never made, it's probably because your username, password, and client IP have not been GRANTed permissions that are needed.
Could be:
your university network; find a network engineer to ask about firewalls.
permission in the MySQL database; find the DBA and ask.
your code; you didn't post enough to tell. Post the whole class.
What's up with that copyright? I'd lose that.
This code works. Modify it so the pertinent parameters match your problem. (Mine uses MySQL 5.1.51 and a table named Party.) When I run it on my local machine, I get a wall time of 641 ms.
package persistence;
import java.sql.*;
import java.util.*;
/**
* DatabaseUtils
* User: Michael
* Date: Aug 17, 2010
* Time: 7:58:02 PM
*/
public class DatabaseUtils
{
/*
private static final String DEFAULT_DRIVER = "org.postgresql.Driver";
private static final String DEFAULT_URL = "jdbc:postgresql://localhost:5432/party";
private static final String DEFAULT_USERNAME = "pgsuper";
private static final String DEFAULT_PASSWORD = "pgsuper";
*/
private static final String DEFAULT_DRIVER = "com.mysql.jdbc.Driver";
private static final String DEFAULT_URL = "jdbc:mysql://localhost:3306/party";
private static final String DEFAULT_USERNAME = "party";
private static final String DEFAULT_PASSWORD = "party";
public static void main(String[] args)
{
long begTime = System.currentTimeMillis();
String driver = ((args.length > 0) ? args[0] : DEFAULT_DRIVER);
String url = ((args.length > 1) ? args[1] : DEFAULT_URL);
String username = ((args.length > 2) ? args[2] : DEFAULT_USERNAME);
String password = ((args.length > 3) ? args[3] : DEFAULT_PASSWORD);
Connection connection = null;
try
{
connection = createConnection(driver, url, username, password);
DatabaseMetaData meta = connection.getMetaData();
System.out.println(meta.getDatabaseProductName());
System.out.println(meta.getDatabaseProductVersion());
String sqlQuery = "SELECT PERSON_ID, FIRST_NAME, LAST_NAME FROM PERSON ORDER BY LAST_NAME";
System.out.println("before insert: " + query(connection, sqlQuery, Collections.EMPTY_LIST));
connection.setAutoCommit(false);
String sqlUpdate = "INSERT INTO PERSON(FIRST_NAME, LAST_NAME) VALUES(?,?)";
List parameters = Arrays.asList( "Foo", "Bar" );
int numRowsUpdated = update(connection, sqlUpdate, parameters);
connection.commit();
System.out.println("# rows inserted: " + numRowsUpdated);
System.out.println("after insert: " + query(connection, sqlQuery, Collections.EMPTY_LIST));
}
catch (Exception e)
{
rollback(connection);
e.printStackTrace();
}
finally
{
close(connection);
long endTime = System.currentTimeMillis();
System.out.println("wall time: " + (endTime - begTime) + " ms");
}
}
public static Connection createConnection(String driver, String url, String username, String password) throws ClassNotFoundException, SQLException
{
Class.forName(driver);
if ((username == null) || (password == null) || (username.trim().length() == 0) || (password.trim().length() == 0))
{
return DriverManager.getConnection(url);
}
else
{
return DriverManager.getConnection(url, username, password);
}
}
public static void close(Connection connection)
{
try
{
if (connection != null)
{
connection.close();
}
}
catch (SQLException e)
{
e.printStackTrace();
}
}
public static void close(Statement st)
{
try
{
if (st != null)
{
st.close();
}
}
catch (SQLException e)
{
e.printStackTrace();
}
}
public static void close(ResultSet rs)
{
try
{
if (rs != null)
{
rs.close();
}
}
catch (SQLException e)
{
e.printStackTrace();
}
}
public static void rollback(Connection connection)
{
try
{
if (connection != null)
{
connection.rollback();
}
}
catch (SQLException e)
{
e.printStackTrace();
}
}
public static List<Map<String, Object>> map(ResultSet rs) throws SQLException
{
List<Map<String, Object>> results = new ArrayList<Map<String, Object>>();
try
{
if (rs != null)
{
ResultSetMetaData meta = rs.getMetaData();
int numColumns = meta.getColumnCount();
while (rs.next())
{
Map<String, Object> row = new HashMap<String, Object>();
for (int i = 1; i <= numColumns; ++i)
{
String name = meta.getColumnName(i);
Object value = rs.getObject(i);
row.put(name, value);
}
results.add(row);
}
}
}
finally
{
close(rs);
}
return results;
}
public static List<Map<String, Object>> query(Connection connection, String sql, List<Object> parameters) throws SQLException
{
List<Map<String, Object>> results = null;
PreparedStatement ps = null;
ResultSet rs = null;
try
{
ps = connection.prepareStatement(sql);
int i = 0;
for (Object parameter : parameters)
{
ps.setObject(++i, parameter);
}
rs = ps.executeQuery();
results = map(rs);
}
finally
{
close(rs);
close(ps);
}
return results;
}
public static int update(Connection connection, String sql, List<Object> parameters) throws SQLException
{
int numRowsUpdated = 0;
PreparedStatement ps = null;
try
{
ps = connection.prepareStatement(sql);
int i = 0;
for (Object parameter : parameters)
{
ps.setObject(++i, parameter);
}
numRowsUpdated = ps.executeUpdate();
}
finally
{
close(ps);
}
return numRowsUpdated;
}
}