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JDBC update using prepared statement

I am trying to update a table using Java JDBC. The method I am using does not throw any errors but the table is not updating. The create table method is below:
public static void Table()
{
Connection c = null;
Statement stmt = null;
try {
Class.forName("org.sqlite.JDBC");
c = DriverManager.getConnection("jdbc:sqlite:WalkerTechCars.db");
System.out.println("Opened database successfully");
stmt = c.createStatement();
String sql = "CREATE TABLE IF NOT EXISTS CUSTOMERS2 " +
"(PHONE TEXT PRIMARY KEY NOT NULL," +
" SURNAME TEXT NOT NULL, " +
" FIRSTNAME TEXT NOT NULL, " +
" HOME TEXT, " +
" ADDRESS TEXT, " +
" POSTCODE Text)";
stmt.executeUpdate(sql);
stmt.close();
c.close();
} catch ( Exception e ) {
System.err.println( e.getClass().getName() + ": " + e.getMessage() );
System.exit(0);
}
System.out.println("Customers2 created successfully");
}
The update method is below:
public static void updateCustomers()
{
Connection c = null;
PreparedStatement pstmt = null;
try {
Class.forName("org.sqlite.JDBC");
c = DriverManager.getConnection("jdbc:sqlite:WalkerTechCars.db");
c.setAutoCommit(false);
System.out.println("Opened database successfully");
String query = "UPDATE CUSTOMERS2 set ADDRESS = ? where PHONE = ? ";
pstmt = c.prepareStatement(query); // create a statement
pstmt.setString(1, "1"); // set input parameter 1
pstmt.setString(2, "DOES THIS WORK"); // set input parameter 2
pstmt.executeUpdate(); // execute update statement
pstmt.close();
c.close();
} catch ( Exception e ) {
System.err.println( e.getClass().getName() + ": " + e.getMessage() );
System.exit(0);
}
System.out.println("Update Completed successfully HELLO");
}
I have tried to find some clear instructions on this but cant find any. I do not really understand JDBC and prepared statement very well

When autoCommit is false (c.setAutoCommit(false);), you must manually commit the transaction...
Add...
c.commit()
After pstmt.executeUpdate();
You code also has a flaw, in that if some kind of error occurs during the preparation or execution of the statement, both the Connection and PreparedStatement could be left open, causing a resource leak
If you're using Java 7+ you can use the try-with-resources feature, for example...
try {
Class.forName("org.sqlite.JDBC");
try (Connection c = DriverManager.getConnection("jdbc:sqlite:WalkerTechCars.db")) {
c.setAutoCommit(false);
System.out.println("Opened database successfully");
String query = "UPDATE CUSTOMERS2 set ADDRESS = ? where PHONE = ? ";
try (PreparedStatement pstmt = c.prepareStatement(query)) {
pstmt.setString(1, "1"); // set input parameter 1
pstmt.setString(2, "DOES THIS WORK"); // set input parameter 2
pstmt.executeUpdate(); // execute update statement
c.commit();
}
} catch (SQLException exp) {
exp.printStackTrace();
}
} catch (ClassNotFoundException exp) {
exp.printStackTrace();
System.out.println("Failed to load driver");
}
This will ensure that regardless of how you leave the try block the resource will be closed.
You might also consider taking a look at the JDBC(TM) Database Access

Your update method will set ADDRESS to 1 if there is any row in table with PHONE = does this work.
Try to put Address in 1st Input parameter and Phone 2nd Input parameter

When a connection is created, it is in auto-commit mode.
We need to use [setAutoCommit] method only when we need to make Auto Commit false and make it manual commit after executing the query.
More details at Oracle site on JDBC Transaction.

Java prepared statement in try-with-resources not working [duplicate]

This question already has answers here:
How should I use try-with-resources with JDBC?
(5 answers)
Closed 8 years ago.
Yesterday multiple people on Stack recommended using try-with-resources. I am doing this for all my database operations now. Today I wanted to change Statement to PreparedStatement to make the queries more secure. But when I try to use a prepared statement in try-with-resources I keep getting errors like 'identifier expected' or ';' or ')'.
What am I doing wrong? Or isnt this possible? This is my code:
try (Connection conn = DriverManager.getConnection(DBURL, DBUSER, DBPASS);
PreparedStatement stmt = conn.prepareStatement("SELECT id FROM users WHERE id = ? LIMIT 1");
stmt.setInt(1, user);
ResultSet rs = stmt.executeQuery()) {
// if no record found
if(!rs.isBeforeFirst()) {
return false;
}
// if record found
else {
return true;
}
} catch (SQLException e) {
// log error but dont do anything, maybe later
String error = "SQLException: " + e.getMessage() + "\nSQLState: " + e.getSQLState() + "\nVendorError: " + e.getErrorCode();
return false;
}

A try-with-resource statement is used to declare (Autoclosable) resources. Connection, PreparedStatement and ResultSet are Autoclosable, so that's fine.
But stmt.setInt(1, user) is NOT a resource, but a simple statement. You cannot have simple statements (that are no resource declarations) within a try-with-resource statement!
Solution: Create multiple try-with-resource statements!
try (Connection conn = DriverManager.getConnection(DBURL, DBUSER, DBPASS)) {
executeStatement(conn);
} catch (SQLException e) {
// log error but dont do anything, maybe later
String error = "SQLException: " + e.getMessage() + "\nSQLState: " + e.getSQLState() + "\nVendorError: " + e.getErrorCode();
return false;
}
private void executeStatement(Connection con) throws SQLException {
try (PreparedStatement stmt = conn.prepareStatement("SELECT id FROM users WHERE id=? LIMIT 1")) {
stmt.setInt(1, user);
try (ResultSet rs = stmt.executeQuery()) {
// process result
}
}
}
(Please note that technically it is not required to put the execution of the SQL statement into a separate method as I did. It also works if both, opening the connection and creating the PreparedStatement are within the same try-with-resource statement. I just consider it good practice to separate connection management stuff from the rest of the code).

try this code:
try (Connection conn = DriverManager.getConnection(DBURL, DBUSER, DBPASS)) {
PreparedStatement stmt = conn.prepareStatement("SELECT id FROM users WHERE id = ? LIMIT 1");
stmt.setInt(1, user);
ResultSet rs = pstmt.executeQuery())
// if no record found
if(!rs.isBeforeFirst()) {
return false;
}
// if record found
else {
return true;
}
} catch (SQLException e) {
// log error but dont do anything, maybe later
String error = "SQLException: " + e.getMessage() + "\nSQLState: " + e.getSQLState() + "\nVendorError: " + e.getErrorCode();
return false;
}
note that here, resource is your Connection and you have to use it in the try block ()

Move
stmt.setInt(1, user);
ResultSet rs = stmt.executeQuery()
...within the try{ /*HERE*/ }
This is because stmt is the resource being created try (/*HERE*/) {} to be used try{ /*HERE*/ }
Try-with-resources
try (/*Create resources in here such as conn and stmt*/)
{
//Use the resources created above such as stmt
}
The point being that everything created in the resource creation block implements AutoClosable and when the try block is exited, close() is called on them all.
In your code stmt.setInt(1, user); is not an AutoCloseable resource, hence the problem.

Execute multiple SQL statements in java

I want to execute a query in Java.
I create a connection. Then I want to execute an INSERT statement, when done, the connection is closed but I want to execute some insert statement by a connection and when the loop is finished then closing connection.
What can I do ?
My sample code is :
public NewClass() throws SQLException {
try {
Class.forName("oracle.jdbc.driver.OracleDriver");
} catch (ClassNotFoundException e) {
System.out.println("Where is your Oracle JDBC Driver?");
return;
}
System.out.println("Oracle JDBC Driver Registered!");
Connection connection = null;
try {
connection = DriverManager.getConnection(
"jdbc:oracle:thin:#localhost:1521:orcl1", "test",
"oracle");
} catch (SQLException e) {
System.out.println("Connection Failed! Check output console");
return;
}
if (connection != null) {
Statement stmt = connection.createStatement();
ResultSet rs = stmt.executeQuery("SELECT * from test.special_columns");
while (rs.next()) {
this.ColName = rs.getNString("column_name");
this.script = "insert into test.alldata (colname) ( select " + ColName + " from test.alldata2 ) " ;
stmt.executeUpdate("" + script);
}
}
else {
System.out.println("Failed to make connection!");
}
}
When the select statement ("SELECT * from test.special_columns") is executed, the loop must be twice, but when (stmt.executeUpdate("" + script)) is executed and done, then closing the connection and return from the class.

Following example uses addBatch & executeBatch commands to execute multiple SQL commands simultaneously.
import java.sql.*;
public class jdbcConn {
public static void main(String[] args) throws Exception{
Class.forName("org.apache.derby.jdbc.ClientDriver");
Connection con = DriverManager.getConnection
("jdbc:derby://localhost:1527/testDb","name","pass");
Statement stmt = con.createStatement
(ResultSet.TYPE_SCROLL_SENSITIVE,
ResultSet.CONCUR_UPDATABLE);
String insertEmp1 = "insert into emp values
(10,'jay','trainee')";
String insertEmp2 = "insert into emp values
(11,'jayes','trainee')";
String insertEmp3 = "insert into emp values
(12,'shail','trainee')";
con.setAutoCommit(false);
stmt.addBatch(insertEmp1);
stmt.addBatch(insertEmp2);
stmt.addBatch(insertEmp3);
ResultSet rs = stmt.executeQuery("select * from emp");
rs.last();
System.out.println("rows before batch execution= "
+ rs.getRow());
stmt.executeBatch();
con.commit();
System.out.println("Batch executed");
rs = stmt.executeQuery("select * from emp");
rs.last();
System.out.println("rows after batch execution= "
+ rs.getRow());
}
}
Result:
The above code sample will produce the following result.The result may vary.
rows before batch execution= 6
Batch executed
rows after batch execution= = 9
Source: Execute multiple SQL statements

In the abscence of the schema or the data contained in each table I'm going to make the following assumptions:
The table special_columns could look like this:
column_name
-----------
column_1
column_2
column_3
The table alldata2 could look like this:
column_1 | column_2 | column_3
---------------------------------
value_1_1 | value_2_1 | value_3_1
value_1_2 | value_2_2 | value_3_2
The table alldata should, after inserts have, happened look like this:
colname
---------
value_1_1
value_1_2
value_2_1
value_2_2
value_3_1
value_3_2
Given these assumptions you can copy the data like this:
try (
Connection connection = DriverManager.getConnection("jdbc:oracle:thin:#localhost:1521:orcl1", "test", "oracle")
)
{
StringBuilder columnNames = new StringBuilder();
try (
Statement select = connection.createStatement();
ResultSet specialColumns = select.executeQuery("SELECT column_name FROM special_columns");
Statement insert = connection.createStatement()
)
{
while (specialColumns.next())
{
int batchSize = 0;
insert.addBatch("INSERT INTO alldata(colname) SELECT " + specialColumns.getString(1) + " FROM alldata2");
if (batchSize >= MAX_BATCH_SIZE)
{
insert.executeBatch();
batchSize = 0;
}
}
insert.executeBatch();
}
A couple of things to note:
MAX_BATCH_SIZE should be set to a value based on your database configuration and the data being inserted.
this code is using the Java 7 try-with-resources feature to ensure the database resources are released when they're finished with.
you haven't needed to do a Class.forName since the service provider mechanism was introduced as detailed in the JavaDoc for DriverManager.

There are two problems in your code. First you use the same Statement object (stmt) to execute the select query, and the insert. In JDBC, executing a statement will close the ResultSet of the previous execute on the same object.
In your code, you loop over the ResultSet and execute an insert for each row. However executing that statement will close the ResultSet and therefor on the next iteration the call to next() will throw an SQLException as the ResultSet is closed.
The solution is to use two Statement objects: one for the select and one for the insert. This will however not always work by default, as you are working in autoCommit (this is the default), and with auto commit, the execution of any statement will commit any previous transactions (which usually also closes the ResultSet, although this may differ between databases and JDBC drivers). You either need to disable auto commit, or create the result set as holdable over commit (unless that already is the default of your JDBC driver).

SQLException: This ResultSet is closed when trying to loop through three resultsets

m trying to loop through 3 resultsets and compare their values. bt its throwing this exception...could someone help me on where am going through?
here is the piece of code:
java.lang.Object[] reconciledPaymentDetails = null;
java.util.Vector shiftsVector = new java.util.Vector(1, 1);
String status = "";
try {
Class.forName("org.postgresql.Driver");
}
catch (ClassNotFoundException ex) {
Logger.getLogger(DBConnection.class.getName()).log(Level.SEVERE, null, ex);
}
try {
connDB = DriverManager.getConnection("jdbc:postgresql://" + hostName + ":" + portNumber + "/" + dbName, userName, password);
System.out.println("Connection established : [" + connDB.toString() + "]");
java.sql.Statement pstmt = connDB.createStatement();
java.sql.Statement pstmtShifts = connDB.createStatement();
java.sql.ResultSet rset = pstmt.executeQuery("SELECT DISTINCT payment_mode,transaction_type, credit FROM ac_cash_collection WHERE shift_no = '" + shiftNumber + "'");
while (rset.next()) {
java.sql.ResultSet rsetShifts = pstmtShifts.executeQuery("SELECT DISTINCT amount, shift_amount FROM ac_shift_collections WHERE shift_no = '" + shiftNumber + "' AND pay_mode ilike '"+rset.getString(1) +"'");
while (rsetShifts.next()) {
java.sql.ResultSet rset2 = pstmt.executeQuery("select debit from ac_cash_book where shift_no='"+shiftNumber+"'");
while (rset2.next()){
double debit =rset2.getDouble("debit");
if((rset2.getDouble("debit")<=0 ))
status = "no_banked";
else if((rset2.getDouble("debit")==rsetShifts.getDouble("amount"))
&& (rsetShifts.getDouble("amount"))< rsetShifts.getDouble("shift_amount"))
status= "BntClosed";
else if (rset2.getDouble(1)==rsetShifts.getDouble("shift_amount"))
status ="bClosed";
shiftsVector.addElement(rset.getString(1)+":"+rsetShifts.getString(1)+":"+status);
}
}
}

The documentation provides a clear explanation of this:
By default, only one ResultSet object per Statement object can be open
at the same time. Therefore, if the reading of one ResultSet object is
interleaved with the reading of another, each must have been generated
by different Statement objects. All execution methods in the Statement
interface implicitly close a statment's current ResultSet object if an
open one exists.
So your options would be:
Use a different Statement instance for each query.
Collect all the results from each ResultSet (i.e. into a Set or a List) before moving on to the next one, and then run the comparison on the collected results instead of directly on the result-sets.

When do we need to call java.sql.Connection.rollback()?

I have to modify a few tables in one function. They must all succeed, or all fail. If one operation fails, I want them all to fail. I have the following:
public void foo() throws Exception {
Connection conn = null;
try {
conn = ...;
conn.setAutoCommit(false);
grok(conn);
conn.commit();
}
catch (Exception ex) {
// do I need to call conn.rollback() here?
}
finally {
if (conn != null) {
conn.close();
conn = null;
}
}
}
private void grok(Connection conn) throws Exception {
PreparedStatement stmt = null;
try {
// modify table "apple"
stmt = conn.prepareStatement(...);
stmt.executeUpdate();
stmt.close();
// modify table "orange"
stmt = conn.prepareStatement(...);
stmt.executeUpdate();
stmt.close();
...
}
finally {
if (stmt != null) {
stmt.close();
}
}
}
I'm wondering if I need to call rollback() in the case that something goes wrong during this process.
Other info: I'm using connection pooling. In the sample above, I'm also making sure to close each PreparedStatement using finally statements as well, just left out for brevity.
Thank you

Yes you need to call rollback if any of your statements fails or you have detected an exception prior to calling commit. This is an old post but the accepted answer is wrong. You can try it for yourself by throwing an exception before commit and observing that your inserts still make it into the database if you do not manually rollback.
JDBC Documentation
https://docs.oracle.com/javase/tutorial/jdbc/basics/transactions.html#call_rollback
Example Correct Usage from the doc
public void updateCoffeeSales(HashMap<String, Integer> salesForWeek)
throws SQLException {
PreparedStatement updateSales = null;
PreparedStatement updateTotal = null;
String updateString =
"update " + dbName + ".COFFEES " +
"set SALES = ? where COF_NAME = ?";
String updateStatement =
"update " + dbName + ".COFFEES " +
"set TOTAL = TOTAL + ? " +
"where COF_NAME = ?";
try {
con.setAutoCommit(false);
updateSales = con.prepareStatement(updateString);
updateTotal = con.prepareStatement(updateStatement);
for (Map.Entry<String, Integer> e : salesForWeek.entrySet()) {
updateSales.setInt(1, e.getValue().intValue());
updateSales.setString(2, e.getKey());
updateSales.executeUpdate();
updateTotal.setInt(1, e.getValue().intValue());
updateTotal.setString(2, e.getKey());
updateTotal.executeUpdate();
con.commit();
}
} catch (SQLException e ) {
JDBCTutorialUtilities.printSQLException(e);
if (con != null) {
try {
System.err.print("Transaction is being rolled back");
con.rollback();
} catch(SQLException excep) {
JDBCTutorialUtilities.printSQLException(excep);
}
}
} finally {
if (updateSales != null) {
updateSales.close();
}
if (updateTotal != null) {
updateTotal.close();
}
con.setAutoCommit(true);
}
}

You don't need to call rollback(). If the connection closes without completing commit() it will be rolled back.
You don't need to set conn to null either; and since the try block starts after conn is initialized (assuming ... cannot evaluate to null) you don't need the != null in finally either.

If you call "commit" then the transaction will be committed. If you have multiple insert/update statements and one of them fails, committing will cause the inserts/updates that didn't fail to commit to the database. So yes, if you don't want the other statements to commit to the db, you need to call rollback. What you are essentially doing by setting autocommit to false is allowing multiple statements to be committed or rolledback together. Otherwise each individual statement will automatically commit.