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Select a postgres database after onnect on java [duplicate]

This question already has an answer here:
What is JDBC counterpart of Postgres' "\connect" command?
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Closed 5 years ago.
This code connects abd create a database ,how can I select the created database to use it?
public class Connect {
public static void main(String[] args) {
Connection connection = null;
try {
Class.forName("org.postgresql.Driver");
connection = DriverManager.getConnection(
"jdbc:postgresql://localhost:5432/","postgres", "12345");
Statement statement = connection.createStatement();
statement.execute("CREATE DATABASE mydb");
//now I hav to connect to mydb
connection.close();
} catch (ClassNotFoundException ex) {
Logger.getLogger(OracleToPostgres.class.getName()).log(Level.SEVERE, null, ex);
} catch (SQLException ex) {
Logger.getLogger(OracleToPostgres.class.getName()).log(Level.SEVERE, null, ex);
}
}
}

Something like this will do ...
Connection con = DriverManager.getConnection("jdbc:postgresql://localhost:5432/mydb", "user", "password");

Connect derby DB to Java

I wanted to connect DB to Java application in Intellij.
I set the classpath correctly, so that javac from cmd is working correct.
I have also downloaded all the jar files needed as a libary, but I still get java.sql.SQLException: No suitable driver found for jdbc:derby
What can be the problem?
public static void main(String[] args) {
try {
Class.forName("org.apache.derby.jdbc.ClientDriver");
} catch(java.lang.ClassNotFoundException e) {
e.printStackTrace();
}
final String DATABASE_URL = "jdbc:derby:myDB;create=true;user=user;password=pass";
try (
Connection connection = DriverManager.getConnection(DATABASE_URL, "user", "pass");
)
{
// ...
}
catch (SQLException sqlException)
{
sqlException.printStackTrace();
}
}

You can try if org.apache.derby.jdbc.EmbeddedDriver works. And it seems your connection url is wrong.
final String DATABASE_URL = "jdbc:derby://localhost:1527/myDB;create=true;user=user;password=pass";
Connection connection = null;
try{
Class.forName("org.apache.derby.jdbc.EmbeddedDriver");
connection = DriverManager.getConnection(DATABASE_URL );
}
catch (Exception e)
{
e.printStackTrace();
}

Connect with DB2 from Java

I try to connect to db2 from java, here is my code:
public class Db2Connection {
public static void main(String[] args) {
String jdbcClassName="com.ibm.db2.jcc.DB2Driver";
String url="jdbc:db2://localhost:50001/TEST";
String user="user1";
String password="pass";
System.out.println("before try-catch");
Connection connection = null;
try {
System.out.println("try");
//Load class into memory
Class.forName(jdbcClassName);
//Establish connection
System.out.println("before conn");
connection = DriverManager.getConnection(url, user, password);
System.out.println("after conn");
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
}finally{
if(connection!=null){
System.out.println("Connected successfully.");
try {
connection.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
}
}
To be clear, I add db2jcc.jar to my project and run code with valid url. Program cannot jump over line:
connection = DriverManager.getConnection(url, user, password);
I receive no errors or exception, application just not execute. I have no idea how deal with it, can anyone help me?

Try, after removing colon like :
String url="jdbc:db2//localhost:50001/TEST";

cannot exexute SQL query wirh OJDBC and Oracle DB (but full working with posgtres JDBC and Postgres DB)

I wrote a java program which retrieve data from a PG gb, process them, and write them in an Oracle DB.
While the PG part is fully working, the Oracle one has issues.
I can connect to the DB, but every query ends with a rollback (ResultSet with Oracle is always null)
Of course i have both PG and Oracle JDBC driver.
Here are my DBs object and testing queries
private final static PostgresDB postgres = new PostgresDB("jdbc:postgresql://192.168.2.23:5432/T18CLEAN", "myPGUser", "myPGPasswd", true);
private final static OracleDB oracle = new OracleDB("jdbc:oracle:thin:#192.168.2.20:1521/EFFEVI.T18FV.IT", "myOracleUser", "myOraclePasswd");
private final static String testPostgres = "SELECT product_pricelist_item.x_product_name FROM public.product_pricelist_item;";
private final static String testOracle = "SELECT EFFEVI.PRESA_ORDINI.PO_CLIENTE FROM EFFEVI.PRESA_ORDINI;";
Then I setup the 2 connections:
PG:
public Connection getConnect() throws ClassNotFoundException {
System.out.println("-------- Posgres JDBC Connection Testing ------");
String url = c_url;
Connection conn = null;
Properties props = new Properties();
props.setProperty("user", user);
props.setProperty("password", passwd);
props.setProperty("ssl", boolToString(sslEnabled));
try{
Class.forName("org.postgresql.Driver");
System.out.println("Postgres JDBC Driver Registered!");
} catch(ClassNotFoundException e) {
System.out.println("Where is your Oracle JDBC Driver?");
e.printStackTrace();
return null;
}
try {
conn = DriverManager.getConnection(url, props);
System.out.println("You made it, take control your Postgres database now!");
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
System.out.println("Failed to make connection to Postgres DB!");
}
return conn;
}
Oracle:
public Connection getConnect(){
Connection connection = null;
System.out.println("-------- Oracle JDBC Connection Testing ------");
try {
Class.forName("oracle.jdbc.driver.OracleDriver");
} catch (ClassNotFoundException e) {
System.out.println("Where is your Oracle JDBC Driver?");
e.printStackTrace();
return connection;
}
System.out.println("Oracle JDBC Driver Registered!");
try {
connection = DriverManager.getConnection(c_url, user, passwd);
} catch (SQLException e) {
System.out.println("Connection Failed! Check output console");
e.printStackTrace();
return connection;
}
if (connection != null) {
System.out.println("You made it, take control your Oracle database now!");
return connection;
} else {
System.out.println("Failed to make connection to Oracle DB!");
}
return connection;
}
After all these pass i perform queries
public ResultSet executeCommand(Connection c, String command) {
Statement st = null;
ResultSet rs = null;
try {
st = c.createStatement();
rs = st.executeQuery(command);
} catch (SQLException e) {
}
if(rs==null){
System.out.println("Failed to Execute command " + command);
} else {
System.out.println("Command Executed: " + command);
}
return rs;
}
Assuming that there are no parameters error... What could it be? Any help?
Thank you very much

Remove a semicolon at the end of the query.
Use this:
private final static String testOracle =
"SELECT EFFEVI.PRESA_ORDINI.PO_CLIENTE FROM EFFEVI.PRESA_ORDINI";
instead of this one:
private final static String testOracle =
"SELECT EFFEVI.PRESA_ORDINI.PO_CLIENTE FROM EFFEVI.PRESA_ORDINI;";
Also don't silently "swallow" an exception in your code:
} catch (SQLException e) {
}
Rethrow the exception, or at least print the error to the log:
} catch (SQLException e) {
log.error("Error while executing query " + command, e);
throw new RuntimeException("Error while executing query " + command, e);
}

Returning the Connection from JDBC into a main method of Java?

Is it possible to return the type Connection?
And use it as a method passed by reference through out the program?
I find it makes the database interaction a lot easier if it is passed as a method.
public static Connection database(String database, String username, String password) {
String url = "jdbc:postgresql:" + database;
//LOAD DRIVER
try {
Class.forName("org.postgresql.Driver");
}
catch (ClassNotFoundException e) {
e.printStackTrace();
}
//CONNECT TO DATABASE
try {
Connection conn = DriverManager.getConnection(url, username, password);
return conn;
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return null;
}
public static void main(String[] args) {
db = database("java_jdbc", "admin", "fake_password_1234");
}

You can do that.
Just remember to invoke close() on the connection to release its resources when done.

package mySystem;
import java.sql.*;
import javax.swing.*;
public class MySqlConnector {
Connection conn = null;
public static Connection ConnectDB() {
try {
Class.forName("com.mysql.jdbc.Driver"); //register jdbc driver
Connection conn = DriverManager.getConnection("jdbc:mysql://localhost/inventory_db", "root", "");
// JOptionPane.showMessageDialog(null, "Connected to db");
return conn;
} catch (Exception e) {
JOptionPane.showMessageDialog(null, e);
return null;
}
}
}