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Why connection still commits automatically after putting setAutoCommit(false)?

I'm using a MySQL database.
I have a code like this :
public class Test {
public static void main(String[] args) throws SQLException {
String url = "....";
String username = "...";
String password = "...";
DriverManager.registerDriver(new Driver());
Connection connection = DriverManager.getConnection(url, username, password);
connection.setAutoCommit(false);
Statement stmt = connection.createStatement();
stmt.execute("create table if not exists customer1\r\n" + "(\r\n"
+ "customer_name varchar(20) not null primary key,\r\n" + "customer_street varchar(20),\r\n"
+ "customer_city varchar(10)\r\n" + ")");
// connection.commit();
connection.close();
}
}
Problem: When I execute this, it creates the table and commits it automatically but it should not.
I did connection.setAutoCommit(false) and commented out connection.commit() for testing, then why it is committing ?
This question (jdbc autocommit(false) doesnt work) didn't help.

Problem: When I execute this, it creates the table and commits it
automatically but it should not.
Right, any DDL will always be committed regardless of autocommit setting.
This behavior is not specific to MySQL, see Autocommit.
Most DBMS (e.g. MariaDB) force autocommit for every DDL statement,
even in non-autocommit mode. In this case, before each DDL statement,
previous DML statements in transaction are autocommitted. Each DDL
statement is executed in its own new autocommit transaction.
Maybe TEMPORARY TABLE might help you.
You can use the TEMPORARY keyword when creating a table. A TEMPORARY
table is visible only within the current session, and is dropped
automatically when the session is closed. This means that two
different sessions can use the same temporary table name without
conflicting with each other or with an existing non-TEMPORARY table of
the same name. (The existing table is hidden until the temporary table
is dropped.)

MySQL DDL, i.e. creating table isn't transactional
ref transactions that cause implicit commit

Data Manipulation statements are transactional, not Data definition statements.
so create/alter table or drop table are still committed.

Can you use JDBC to connect to just an instance without specifying a database?

I am working on an JAVA app that evaluates the data and log sizes of all databases on an instance and mails a monthly report. I am currently working with SQLServer2014. I am using an SQL query that calculates the size of all databases by querying sys.master_files.
The problem is that when using JDBC to make the query, it returns the error:
java.sql.SQLException: No suitable driver found for jdbc:microsoft:sqlserver://localhost"
I have tried connecting to particular databases and that works fine. Is there any way to do this query directly to sys.master_files using JDBC? Or is there a smarter way altogether to accomplish the same result?
Thanks

Your "No suitable driver found" error is simply due to a malformed connection URL. jdbc:microsoft:sqlserver is not valid.
As for connecting to an instance without specifying a particular database, this works fine for me:
// NB: no databaseName specified in the following
String connectionUrl = "jdbc:sqlserver://localhost;instanceName=SQLEXPRESS;integratedSecurity=true";
try (Connection conn = DriverManager.getConnection(connectionUrl)) {
String sql = "SELECT name FROM sys.master_files WHERE type_desc='ROWS' ORDER BY database_id";
try (
Statement st = conn.createStatement();
ResultSet rs = st.executeQuery(sql)) {
while (rs.next()) {
System.out.println(rs.getString(1));
}
}
} catch (Exception e) {
e.printStackTrace(System.err);
}
Note that sys.master_files is a system view that is available in all databases, so AFAIK it doesn't matter what the current database (catalog) is when you call it.

JDBC : Batch insert not inserting value to database

I have to execute multiple insert queries using JDBC for which I am trying to execute batch statement. Everything works fine in my code but when i try to see values in the table, the table is empty.
Here is the code :
SessionImpl sessionImpl = (SessionImpl) getSessionFactory().openSession();
Connection conn = (Connection) sessionImpl.connection();
Statement statement = (Statement) conn.createStatement();
for (String query : queries) {
statement.addBatch(query);
}
statement.executeBatch();
statement.close();
conn.close();
And the
List<String> queries
contains insert queries like:
insert into demo values (null,'Sharmzad','10006','http://demo.com','3 Results','some values','$44.00','10006P2','No Ratings','No Reviews','Egypt','Duration: 8 hours','tour','Day Cruises');
And the table structure is like:
create table demo ( ID INTEGER PRIMARY KEY AUTO_INCREMENT,supplierName varchar(200),supplierId varchar(200),supplierUrl varchar(200),totalActivities varchar(200),activityName varchar(200),activityPrice varchar(200),tourCode varchar(200),starRating varchar(200),totalReviews varchar(200),geography varchar(200),duration varchar(200),category varchar(200),subCategory varchar(200));
No exception is thrown anywhere but no value is inserted. Can someone explain?

Most JDBC drivers use autocommit, but some of them do not. If you don't know, you should use either .setAutoCommit(true) before the transaction or .commit() after it..

Could be a transaction issue. Perhaps you're not committing your transaction? If so, then it is normal not to see anything in the database.
You can check if this is the case by running a client in READ_UNCOMMITTED transaction mode, right after .executeBatch(); (but before close()) and see if there are any rows.

You don't should assign a value to ID add supply all the others columns name
insert into demo
(
supplierName
,supplierId
,supplierUrl
,totalActivities
,activityName
,activityPrice
,tourCode
,starRating
,totalReviews
,geography
,duration
,category
,subCategory
)
values (
'Sharmzad'
,'10006'
,'http://demo.com'
,'3 Results'
,'some values'
,'$44.00'
,'10006P2'
,'No Ratings'
,'No Reviews'
,'Egypt'
,'Duration: 8 hours
','tour'
,'Day Cruises'
);
and add commit to your code

Java Statement.executeUpdate(sql) not working when executeQuery(sql) works

I have a wierd behavior in a Java application.
It issues simple queries and modifications to a remote MySQL database. I found that queries, run by executeQuery() work just fine, but inserts or delete to the database run through executeUpdate() will fail.
Ruling out the first thing that comes to mind: the user the app connects with has correct privilledges set up, as the same INSERT run from the same machine, but in DBeaver, will produce the desired modification.
Some code:
Connection creation
Class.forName("com.mysql.jdbc.Driver");
connection = DriverManager.getConnection(url, user, pass);
Problematic part:
Statement parentIdStatement = connection.createStatement();
String parentQuery = String.format(ProcessDAO.GET_PARENT_ID, parentName);
if (DEBUG_SQL) {
plugin.getLogger().log(Level.INFO, parentQuery);
}
ResultSet result = parentIdStatement.executeQuery(parentQuery);
result.first();
parentId = result.getInt(1);
if (DEBUG_SQL) {
plugin.getLogger().log(Level.INFO, parentId.toString()); // works, expected value
}
Statement createContainerStatement = connection.createStatement();
String containerQuery = String.format(ContainerDAO.CREATE_CONTAINER, parentId, myName);
if (DEBUG_SQL) {
plugin.getLogger().log(Level.INFO, containerQuery); // works when issued through DBeaver
}
createContainerStatement.executeUpdate(containerQuery); // does nothing
"DAOs":
ProcessDAO.GET_PARENT_ID = "SELECT id FROM mon_process WHERE proc_name = '%1$s'";
ContainerDAO.CREATE_CONTAINER = "INSERT INTO mon_container (cont_name, proc_id, cont_expiry, cont_size) VALUES ('%2$s', %1$d, CURRENT_TIMESTAMP(), NULL)";
I suspect this might have to do with my usage of Statement and Connection.
This being a lightweight lightly-used app, I went to simplicity, so no framework, and no specific isntructions regarding transactions or commits.

So, in the end, this code was just fine. It worked today.
To answer the question: where to look first in a similar case (SELECT works but UPDATE / INSERT / DELETE does not)
If rights are not the problem, then there is probably a lock on the table you try to modify. In my case, someone left with an uncommited transaction open.
Proper SQL exceptions logging (which was suboptimal in my case) will help you figure it out.

Creating a "Java DB" database and associated tables in main checking to see if they exist?

I'm creating an applicaation on Netbeans 7! I'd like my application to have a little code in main so that it can create a Java DB connection checking to see if the database and the associate tables exist, if not create the database and the tables in it. If you could provide a sample code, it'd be just as great! I have already looked at http://java.sun.com/developer/technicalArticles/J2SE/Desktop/javadb/ but I'm still not sure how to check for an existing database before creating it!

I'd like my application to have a little code in main so that it can create a Java DB connection checking to see if the database and the associate tables exist, if not create the database and the tables in it.
You can add the create=true property, in the JDBC URL. This creates a Derby database instance if the database specified by the databaseName does not exist at the time of connection. A warning is issued if the database already exists, but as far as I know, no SQLException will be thrown.
As far as creation of the tables is concerned, this is best done on application startup before you access the database for typical transactional activity. You will need to query the SYSTABLES system table in Derby/JavaDB to ascertain whether your tables exist.
Connection conn;
try
{
String[] tableNames = {"tableA", "tableB"};
String[] createTableStmts = ... // read the CREATE TABLE SQL statements from a file into this String array. First statement is for the tableA, and so on.
conn = DriverManager.getConnection("jdbc:derby:sampleDB;create=true");
for(int ctr =0 ; ctr < tableNames.length; ctr++)
{
PreparedStatement pStmt = conn.prepareStatement("SELECT t.tablename FROM sys.systables t WHERE t.tablename = ?");
pStmt.setString(1, tableNames[ctr]);
ResultSet rs = pStmt.executeQuery();
if(!rs.next())
{
// Create the table
Statement stmt = conn.createStatement();
stmt.executeUpdate(createTableStmts[ctr]);
stmt.close();
}
rs.close();
pStmt.close();
}
}
catch (SQLException e)
{
throw new RuntimeException("Problem starting the app...", e);
}
Any non-existent tables may then be created. This is of course, not a good practice, if your application has multiple versions, and the schema varies from one version of the application to another. If you must handle such a scenario, you should store the version of the application in a distinct table (that will usually not change across versions), and then apply database delta scripts specific to the newer version, to migrate your database from the older version. Using database change management tools like DbDeploy or LiquiBase is recommended. Under the hood, the tools perform the same operation by storing the version number of the application in a table, and execute delta scripts having versions greater than the one in the database.
On a final note, there is no significant difference between JavaDB and Apache Derby.

I don't know how much Oracle changed Derby before rebranding it, but if they didn't change too much then you might be helped by Delete all tables in Derby DB. The answers to that question list several ways to check what tables exist within a database.
You will specify the database when you create your DB connection; otherwise the connection will not be created successfully. (The exact syntax of this is up to how you are connecting to your db, but the logic of it is the same as in shree's answer.)

The create=true property will create a new database if it is not exists. You may use DatabaseMetadata.getTables() method to check the existence of Tables.
Connection cn=DriverManager.getConnection("jdbc:derby://localhost:1527/testdb3;create=true", "testdb3", "testdb3");
ResultSet mrs=cn.getMetaData().getTables(null, null, null, new String[]{"TABLE"});
while(mrs.next())
{
if(!"EMP".equals(mrs.getString("TABLE_NAME")))
{
Statement st=cn.createStatement();
st.executeUpdate("create table emp (eno int primary key, ename varchar(30))");
st.close();;
}
}
mrs.close();
cn.close();

Connection conn = getMySqlConnection();
System.out.println("Got Connection.");
Statement st = conn.createStatement();
String tableName = ur table name ;
String query = ur query;
Statement stmt = null;
ResultSet rs = null;
try {
stmt = conn.createStatement();
rs = stmt.executeQuery(query);
System.out.println("Exist");;
}
catch (Exception e ) {
// table does not exist or some other problem
//e.printStackTrace();
System.out.println("Not Exist");
}
st.close();
conn.close();