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How to get the list of all database names from a Sybase DB Server in java

I want to get the list of all database names from a Sybase DB server. I can connect the Sybase db through Java, but don't know how to get the list of database names. I am using jconn4 jar file.
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
import com.sybase.jdbc4.jdbc.SybDriver;
public class ConnectToSybase {
public static Connection conn = null;
public static Statement stmt = null;
public static SybDriver sybDriver = null;
public static ResultSet rs = null;
public static String dbServerIP = "10.10.10.11";
public static String portNo = "5000";
public static String dbName = "NewDB";
public static void main(String[] args) {
try {
Class.forName("com.sybase.jdbc4.jdbc.SybDriver").newInstance();
System.out.println("Driver loaded");
conn = DriverManager.getConnection("jdbc:sybase:Tds:" + dbServerIP + ":" + portNo, "usrname", "password");
stmt = conn.createStatement();
} catch (Exception e) {
System.out.println("In exception");
e.printStackTrace();
} finally {
try {
rs.close();
stmt.close();
conn.close();
} catch (Exception e) {
}
}
}
}

I found myself a working code.
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
import com.sybase.jdbc4.jdbc.SybDriver;
public class ConnectToSybase {
public static Connection conn = null;
public static Statement stmt = null;
public static SybDriver sybDriver = null;
public static ResultSet rs = null;
public static String dbServerIP = "10.10.10.11";
public static String portNo = "5000";
public static String dbName = "NewDB";
public static void main(String[] args) {
try {
Class.forName("com.sybase.jdbc4.jdbc.SybDriver").newInstance();
System.out.println("Driver loaded");
conn = DriverManager.getConnection("jdbc:sybase:Tds:" + dbServerIP + ":" + portNo, "usrname", "password");
stmt = conn.createStatement();
List<String> dbList = new ArrayList<String>();
// getting list of DB names from the DB server
ResultSet rs = conn.getMetaData().getCatalogs();
while (rs.next()) {
dbList.add(rs.getString(1));
}
for (String list : dbList) {
System.out.println(list);
}
} catch (Exception e) {
System.out.println("In exception");
e.printStackTrace();
} finally {
try {
rs.close();
stmt.close();
conn.close();
} catch (Exception e) {
}
}
}
}

JDBC programming

I am working in command prompt this is my code
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
public class JDBC {
static {
try {
Class.forName("com.mysql.jdbc.Driver");
} catch (ClassNotFoundException cnf) {
System.out.println("Driver could not be loaded: " + cnf);
}
}
public static void main(String[] args)
{
String connectionUrl = "jdbc:mysql://localhost:3306/mysql";
String dbUser = "root";
String dbPwd = "admin";
Connection conn;
ResultSet rs;
String queryString = "SELECT ID, NAME FROM exptable";
try {
conn = DriverManager.getConnection(connectionUrl, dbUser, dbPwd);
Statement stmt = conn.createStatement();
// INSERT A RECORD
stmt.executeUpdate("INSERT INTO exptable (name) VALUES (\"TINU K\")");
// SELECT ALL RECORDS FROM EXPTABLE
rs = stmt.executeQuery(queryString);
System.out.println("ID \tNAME");
System.out.println("============");
while (rs.next()) {
System.out.print(rs.getInt("id") + ".\t" + rs.getString("name"));
System.out.println();
}
if (conn != null) {
conn.close();
conn = null;
}
} catch (SQLException sqle) {
System.out.println("SQL Exception thrown: " + sqle);
}
}
}
i am getting error like
java.lang.ClassNotFoundException and java.sql.SQLException
so may i know what mistake have i made

You might have missed the classpath in your java command. While executing from command prompt you must mention the class path along with your command.
java -cp
ex:
java -cp /home/test/jars:/home/test/src com.test.Lab

SQLException Operation not allowed after ResultSet closed

I am attempting to write a JUnit test for a query which is retrieved via a textbox in an html form. The text retrieval has been tested and works but my unit test is failing. I am using 2 relevant classes: QueryController and QueryControllerTest. I have been playing around with when and what I am closing in these two classes and keep getting the error: Operation not allowed after ResultSet closed.
QueryControllerTest.java
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import org.junit.Test;
import static org.junit.Assert.*;
public class QueryControllerTest {
#Test
public void testQuery() {
ResultSet testRs = null;
Connection conn = null;
try {
Class.forName("com.mysql.jdbc.Driver");
String connectionUrl = "jdbc:mysql://localhost:3306/test";
String connectionUser = "root";
String connectionPassword = "GCImage";
conn = DriverManager.getConnection(connectionUrl,
connectionUser, connectionPassword);
Query testQuery = new Query();
testQuery
.setQuery("select * from service_request where FN_contact = 'Greg'");
testRs = QueryController.executeSelect(conn, testQuery);
assertEquals("Laughlin", testRs.getString("LN_contact"));
assertEquals("Hello World", testRs.getString("Notes"));
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
} finally {
try {
testRs.close();
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
}
QueryController.java
import java.util.Map;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.RequestMapping;
#Controller
public class QueryController {
#RequestMapping(value = "/query")
public String processRegistration(#ModelAttribute("query") Query query,
Map<String, Object> model) {
String queryString = query.getQuery();
if (queryString != null && !queryString.isEmpty()) {
System.out.println("query (from controller): " + queryString);
Connection conn = null;
try {
Class.forName("com.mysql.jdbc.Driver");
String connectionUrl = "jdbc:mysql://localhost:3306/test";
String connectionUser = "root";
String connectionPassword = "GCImage";
conn = DriverManager.getConnection(connectionUrl,
connectionUser, connectionPassword);
if (queryString.toLowerCase().startsWith("select")) {
ResultSet rs = executeSelect(conn, query);
} else {
int rowsUpdated = executeUpdate(conn, query);
System.out.println(rowsUpdated + " rows updated");
}
} catch (Exception e) {
e.printStackTrace();
}
}
return "query";
}
public static ResultSet executeSelect(Connection conn, Query query) {
ResultSet rs = null;
Statement stmt = null;
try {
stmt = conn.createStatement();
rs = stmt.executeQuery(query.getQuery());
while (rs.next()) {
String id = rs.getString("ID");
String firstName = rs.getString("FN_Contact");
String lastName = rs.getString("LN_Contact");
String notes = rs.getString("Notes");
System.out.println("ID: " + id + ", First Name: " + firstName
+ ", Last Name: " + lastName + ", Notes: " + notes);
}
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
if(rs!=null){
rs.close();
}
if(stmt != null){
stmt.close();
}
if (conn != null)
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
return rs;
}
}

QueryController.executeSelect is calling rs.close(), but then your assertEquals in QueryControllerTest.testQuery are calling methods on testRS. As executeSelect is returning the resultset, closing it first doesn't make sense. Further, executeSelect is being passed the connection, so it shouldn't be closing that either (what happens if the caller wants to do two different selects on the same connection?).

I think the problem is because you are creating two connections. Try to only instantiate the connection of QueryController class for your test. You will need to provide the connection. After you store it in a variable to run the query.
Connection con = QueryController.getConnection ();

JDBC - Retrieve entire data as a List

I'm trying to build a class that retrieves each row from a MySQL table and store it to a List but my code doesn't compile and throws me an error
Error: Main method not found in class
MySQLAccountsDatabankReader,
please define the main method as: public static void main(String[]
args)
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;
public class MySQLAccountsDatabankReader {
private static List<String[]> accounts;
public MySQLAccountsDatabankReader(String[] args) {
Connection con = null;
Statement st = null;
ResultSet rs = null;
String url = "jdbc:mysql://localhost:3306/test";
String user = "root";
String password = "mysql";
try {
con = DriverManager.getConnection(url, user, password);
st = con.createStatement();
rs = st.executeQuery("SELECT * FROM test.accounts;");
if (rs.next()) {
ArrayList<String[]> accounts = new ArrayList<String[]>();
rs = st.executeQuery("SELECT * FROM test.accounts;");
int columnCount = rs.getMetaData().getColumnCount();
while (rs.next()) {
String[] row = new String[columnCount];
for (int i = 0; i < columnCount; i++) {
row[i] = rs.getString(i + 1);
}
accounts.add(row);
}
}
} catch (SQLException ex) {
Logger lgr = Logger.getLogger(MySQLAccountsDatabankReader.class
.getName());
lgr.log(Level.SEVERE, ex.getMessage(), ex);
} finally {
try {
if (rs != null) {
rs.close();
}
if (st != null) {
st.close();
}
if (con != null) {
con.close();
}
} catch (SQLException ex) {
Logger lgr = Logger.getLogger(MySQLAccountsDatabankReader.class
.getName());
lgr.log(Level.WARNING, ex.getMessage(), ex);
}
}
return accounts;
}
}
Revision 0.2 - I've got the following compilation error - Exception in thread "main" java.lang.Error: Unresolved compilation problems:
accounts cannot be resolved
accounts cannot be resolved to a variable
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;
public class MySQLAccountsDatabankReader {
public static void main(String[] args) {
MySQLAccountsDatabankReader reader = new MySQLAccountsDatabankReader();
List<String[]> accounts = reader.getAccounts();
}
public List<String[]> getAccounts() {
Connection con = null;
Statement st = null;
ResultSet rs = null;
String url = "jdbc:mysql://localhost:3306/test";
String user = "root";
String password = "mysql";
try {
con = DriverManager.getConnection(url, user, password);
st = con.createStatement();
rs = st.executeQuery("SELECT * FROM test.accounts;");
if (rs.next()) {
rs = st.executeQuery("SELECT * FROM test.accounts;");
int columnCount = rs.getMetaData().getColumnCount();
while (rs.next()) {
String[] row = new String[columnCount];
for (int i = 0; i < columnCount; i++) {
row[i] = rs.getString(i + 1);
}
accounts.add(row);
}
return accounts;
}
} catch (SQLException ex) {
Logger lgr = Logger.getLogger(MySQLAccountsDatabankReader.class
.getName());
lgr.log(Level.SEVERE, ex.getMessage(), ex);
} finally {
try {
if (rs != null) {
rs.close();
}
if (st != null) {
st.close();
}
if (con != null) {
con.close();
}
} catch (SQLException ex) {
Logger lgr = Logger.getLogger(MySQLAccountsDatabankReader.class
.getName());
lgr.log(Level.WARNING, ex.getMessage(), ex);
}
}
}
}

Compiler errors are usually a good indicator of what is wrong - you need a main method.
Also, non-declarative statements need to be in a method, constructor or static initializer rather than in the class code block. Place your JDBC code within a method. Here you need a method that will return accounts to match your return statement. Also you need to create an instance of List, e.g. ArrayList to return.
private List<String[]> getAccounts() {
List<String[]> accounts = new ArrayList<String[]>();
...
return accounts;
}
and add a main method entry point:
public static void main(String[] args) {
MySQLAccountsDatabankReader reader = new MySQLAccountsDatabankReader();
List<String[]> accounts = reader.getAccounts();
...
}

Add main method:
public static void main(String [] args) {
new MySQLAccountsDatabankReader(args);
}

Error while running JDBC on postgres

This is my CreateQuery.java class .
package DbConnect;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
public class CreateQuery {
Connection conn;
public CreateQuery() throws ClassNotFoundException, SQLException, IOException {
conn=new DbAccess().returnDatabaseConnection();
}
public int addNewLayertoDB(){
try {
PreparedStatement statement = null;
//String table_name = feature_name + "_" + shape;
String query = "SELECT the_geom from bbmp ";
statement = conn.prepareStatement(query);
//statement.setString(1, feature_name);
ResultSet rs = statement.executeQuery();
rs.close();
return 1;
} catch (SQLException ex) {
System.out.println("Sql exception");
return 0;
}
}
public void closeConn() throws SQLException {
if (conn != null) {
this.conn.close();
}
}
public static void main(String args[]) throws FileNotFoundException, IOException, ClassNotFoundException, SQLException{
CreateQuery cq = new CreateQuery();
cq.addNewLayertoDB();
cq.closeConn();
}
}
This is my DbConnect class
package DbConnect;
import java.sql.DriverManager;
import java.sql.Connection;
import java.sql.SQLException;
public class DbAccess{
public static void main(String[] argv) {
System.out.println("-------- PostgreSQL " +
"JDBC Connection Testing ------------");
try {
Class.forName("org.postgresql.Driver");
} catch (ClassNotFoundException e) {
System.out.println("Where is your PostgreSQL JDBC Driver? " +
"Include in your library path!");
e.printStackTrace();
return;
}
System.out.println("PostgreSQL JDBC Driver Registered!");
Connection connection = null;
try {
connection = DriverManager.getConnection(
"jdbc:postgresql://127.0.0.1:5432/Ethermap","postgres", "*******");
} catch (SQLException e) {
System.out.println("Connection Failed! Check output console");
e.printStackTrace();
return;
}
if (connection != null){
System.out.println("You made it, take control your database now!");
}else{
System.out.println("Failed to make connection!");
}
}
public Connection returnDatabaseConnection() {
System.out.println("DB not connected");
return null;
}
}
The error I am getting when I run CreateQuery is
DB not connected
Exception in thread "main" java.lang.NullPointerException
at DbConnect.CreateQuery.addNewLayertoDB(CreateQuery.java:24)
at DbConnect.CreateQuery.main(CreateQuery.java:45)
What is the error ? And How do I debug it ?

The method returnDatabaseConnection() that you call in the constructor of CreateQuery always returns null, so it's not a surprise that your connection object is null.