We Keep Coding

How To Improve SQL Connection

Hello every body I'm working on application which is sends data from android app to MS-SQL server and main windows software in C#, which is receives data from MS-SQl server.
The problem is the programs takes too time to build a connection especially in android app some times it crash the app.
By the way the Internet speed some times goes week in our country.
I searched for a solution but not found in internet and I cannot figure out any way to solve it.
And I see the Viber, Watsapp, Massenger ... etc it sends data instantly or synchronously even if Internet speed is week.
So can I get some help and suggestion.
And there is a connection Helper method :
public Connection connections(){
IP="www.examlple.net";
DB="DB_test";
DBUserName="admin";
DBPassword="*****";
StrictMode.ThreadPolicy policy= new StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);
Connection connection=null;
String connectionURL=null;
try {
Class.forName("net.sourceforge.jtds.jdbc.Driver").newInstance();
connectionURL ="jdbc:jtds:sqlserver://"+IP+";DatabaseName="+DB+";integratedSecurity=true;user="+DBUserName+";password="+DBPassword;
connection = DriverManager.getConnection(connectionURL);
} catch (SQLException | ClassNotFoundException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (InstantiationException e) {
e.printStackTrace();
}
return connection;
}

For the sake of completeness, with JTDS you can set both a loginTimeout and a socketTimeout on a connection string. Refer to the remarks on these here.
But as others have said, you should go through a web API of some sort. Do you really want to expose your SQL server to the internet?
Also, I just noticed you have specified integrated security=true, and you have also specified a username and password. You can't do that. One is for windows auth (integrated security) and the other is for SQL auth (user and password). You would have to use a username and password. But don't. Don't do this. go through a web API.

Issue connecting to Localhost MySQL Database

I am getting an error: com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Could not create connection to database server.
EDIT: Link to the Stack Trace
Here is the last "part" of the error, saying it's a NullPointerException:
at armyofdragons.mule.mysql.Database.<init>(Database.java:28)
at Main.main(Main.java:6)
Caused by: java.lang.NullPointerException
at com.mysql.jdbc.ConnectionImpl.getServerCharset(ConnectionImpl.java:2997)
at com.mysql.jdbc.MysqlIO.sendConnectionAttributes(MysqlIO.java:1934)
at com.mysql.jdbc.MysqlIO.proceedHandshakeWithPluggableAuthentication(MysqlIO.java:1863)
at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1226)
at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2253)
at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2284)
... 14 more
`
My URL String:
"jdbc:mysql://127.0.0.1:3306/schemaname?useUnicode=true&characterEncoding=UTF-8&zeroDateTimeBehavior=convertToNull&serverTimezone=GMT"
My Connection code snippet:
connection = null;
try {
Class.forName("com.mysql.jdbc.Driver").newInstance();
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (InstantiationException e) {
e.printStackTrace();
}
try {
connection = DriverManager.getConnection(URL, "admin", "passwordcensored123");
} catch (SQLException e) {
e.printStackTrace();
}
I have used the proper schema/database name, username, password, and every other "requirement" needed. I also set the bind-address to 127.0.0.1 and port to 3306. The database is ONLINE and I have made sure that the service is RUNNING.

I found out the issue. I was using the wrong version of JDBC / J Connector. A previous StackerOverflow post that I was looking at that provided a solution to adding it to IntelliJ was old and I did not check if it was the up-to-date version or not.
For anyone wanting to know how to add it to IntelliJ, go to Project Structure -> Libraries -> Add (+) -> Add from Maven... -> Enter "mysql:mysql-connector-java:8.0.11" -> Click "Okay".

According to https://dev.mysql.com/doc/connector-j/5.1/en/connector-j-usagenotes-connect-drivermanager.html you can use the actual jdbc connection string in DriverManager.getConnection(), have you tried that?
This sort of thing might be very well also a MySql server vs connector version incompatibility issue. Double check your connector version.
Your snippet is a bit tiny, you might want to paste a bit more generously.

Connecting android app to local MS SQL database

I'm trying to connect my Android app to my local machine database MS SQL. This is my connection string:
jdbc:jtds:sqlserver://localhost:1433/DajSve;encrypt=false;user=root;password=null;instance=FALE//SQLEXPRESS;
And I got this error:
java.sql.SQLException: Network error IOException: failed to connect to localhost/127.0.0.1 (port 1433): connect failed: ECCONREFUSED (Connection refused)
I tried a lot of things. Changed a connection string a lot of times, enabled TCP/IP and set it to port 1433, also turned off firewall but nothing helped. I'm always getting the same SQL Exception. I'm using SQL Server 2016..
try {
Class.forName(className).newInstance();
connection = DriverManager.getConnection("jdbc:jtds:sqlserver://localhost:1433/DajSve;encrypt=false;user=root;password=null;instance=FALE//SQLEXPRESS;");
System.out.print("Uspjesno spojeni na bazu");
Statement stmt = connection.createStatement();
ResultSet reset = stmt.executeQuery("select * from Korisnik");
if (!reset.isBeforeFirst() ) {
System.out.println("nema podataka");
}else{
System.out.println("ima podataka");
}
} catch (SQLException e) {
e.printStackTrace();
System.out.print("Greska pri spajanju na bazu");
} catch (ClassNotFoundException e){
System.out.print("Greska - klasa nije pronađena");
} catch (InstantiationException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
}
I know there is a lot of similar questions but none of the answers have helped

failed to connect to localhost/127.0.0.1
Your Android device isn't running a SQL Server. Give the actual server address on your network (but actually don't because you shouldn't be storing database credentials as part of your app, plus persistent JDBC connections kill battery life).
It's not a local database when your code exists on a remote device
You will actually want to create a new application that is acts as a backend API between your Android app and the database, where you can expose functions that connect to your database and parse the results there rather than doing it all in the Android app

Difficulty connecting to database using SQLserver jdbc

I'm trying to connect to my database using sqljdbc4, I'm pretty new to this so i followed a couple of tutorial but it still doesn't seem to work, When i try to run the program i get this Exception:
com.microsoft.sqlserver.jdbc.SQLServerException: Login failed for user ''. ClientConnectionId:f181fd37-7e28-4392-ac86-02914c2090e1
at com.microsoft.sqlserver.jdbc.SQLServerException.makeFromDatabaseError(SQLServerException.java:216)
And this is my code:
try {
Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");
Connection con = DriverManager.getConnection("jdbc:sqlserver://localhost:1433;databaseName=DBank;","","");
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
}
return null;

You are not passing any authentication credentials. If you want to use integrated security (windows authentication), then you need to explicitly specify that in your connection URL and you need to load the native library required for this.
See Connecting with Integrated Authentication On Windows on Windows on MSDN.
This essentially comes down to including the folder containing the (32 bit or 64 bit) sqljdbc_auth.dll in the java.library.path system property (see link for details) and adding integratedSecurity=true to your connection string:
DriverManager.getConnection(
"jdbc:sqlserver://localhost:1433;databaseName=DBank;integratedSecurity=true");

You are passing empty username and password while connecting to the database in getConnection method:
DriverManager.getConnection("jdbc:sqlserver://localhost:1433;databaseName=DBank;","","");
Try supplying the db username and password, for example:
DriverManager.getConnection("jdbc:sqlserver://localhost:1433;databaseName=DBank;","myusername","mypassword");

NullPointerException in "DriverManager.getConnection" method

I have a problem establishing an connection to my MySql database via Java/Android. I have a database file (MyDatabase.db) on a Windows7 computer in my network. When I'm developing from another Windows7 computer (the file is accessible via the Windows Explorer and I can make changes to the database via SQLDatabaseExplorer) out of Eclipse the following Code works, but when installing my Application on my Galaxy Tab the "DriverManager.getConnection()" returns null.
try {
String url = "http://192.168.178.21/Users/test/userdata/Database/MyDatabase.db";
Class.forName ("com.mysql.jdbc.Driver");
Connection connection = DriverManager.getConnection (url);
System.out.println ("Database connection established");
} catch (SQLException e) {
Log.d("SQLException", "e.toString()");
}
The SQLException logged in LogCat is:
java.sql.SQLException: path to '//192.168.178.21/Users/test/userdata/Database/MyDatabase.db': '/192.168.178.21' does not exist
I guess my problem lies in the url String...? But I did not figure out how to change it, so that the connection can be established.
Thanks for any help,
Tim
EDIT:
Thanks for your help so far! I have written the question yesterday out of my mind, without looking onto my code... I'm sorry for that, because I have mixed up a lot of things... It is not a MySql-database but a sqlite-database... But I think that doesn't change a lot in coding. I'm using an jdbc sqlite driver. When starting the lines below in an Java-Eclipse Project everything works fine and the connection can be established. But on my Device I still got the Nullpointer...
Yesterday I have changed my code so that it should fit your advices. But the problem still resists... To be sure that it does not have to do with some rights or network settings I have copied the DB-File onto my Androiddevice and tried to connect to it directly with the following lines of code:
try {
Class.forName("org.sqlite.JDBC");
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
Connection conn = DriverManager.getConnection("jdbc:sqlite://mnt/sdcard/MyVideos34.db");
if (conn == null) {
Log.d("ConnectionError", "Connection is null");
return;
}
But also here getConnection throws a NullPointer and I don't know why... Did somebody have a assumption why the connection can be established out of Eclipse and fails on my Androiddevice? May I could have a wrong driver, that does not work from the device, but from Eclipse...?
Thanks in advance!

The url format for the MYSQL conenction string is
jdbc:mysql://[host][,failoverhost...][:port]/[database] »
[?propertyName1][=propertyValue1][&propertyName2][=propertyValue2]...
If the host name is not specified, it defaults to 127.0.0.1. If the port is not specified, it defaults to 3306, the default port number for MySQL servers.
jdbc:mysql://[host:port],[host:port].../[database] »
[?propertyName1][=propertyValue1][&propertyName2][=propertyValue2]...
Here is a sample connection URL:
jdbc:mysql://localhost:3306/sakila?profileSQL=true
please change accordingly

JDBC urls have the form : jdbc:mysql:/// but look at the duplicate code. You probably don't want to connect directly to a database from a mobile like this but will prefer a web service wrapper to do it.

try {
String url = "jdbc:mysql://localhost:3306/MyDatabase?user=root&password=root";
Class.forName ("com.mysql.jdbc.Driver").newInstance();
Connection connection = DriverManager.getConnection (url);
System.out.println ("Database connection established");
} catch (SQLException e) {
System.out.println("SQLException" + e.toString());
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (InstantiationException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
}