Why changes arent seen when i re-conect to my Database through a Java API?

[esgol]

Hi, I have a simple Java API, an ATM which is a window with cardlayout

I conect with The database returns that the Credit Amount is 0 and i disconect

I go to deposit money press 40$ and in the event listener the database returns that the credit Amount is 40. all ok and i disconnect

BUT IF I GO TO "see remaining credit" i re-conect inside the button listeners and says me Amount 0 AGAIN!! :eek:

WHY? :eek:

edit:examples deleted due to complexity

[esgol]

Here i have a more clear example.
I conect to a database, i select its table (already created ( seems the only thing that holds lol )
We see amount 0
We update it to +40
We re select it now its ok 40

However if you re-run the programma you always get the same result while you should get 80 the 2ond time 120 the 3rd etc...

import java.sql.*;

public class MysqlConnect{
public static void main(String[] args) {

//CONNECT
System.out.println("MySQL Connect Example.");
Connection conn = null;
String url = "jdbc:mysql://localhost:3306/";
String dbName = "MySQL";
String driver = "com.mysql.jdbc.Driver";
String userName = "root";
String password = "esgordoreth";
try {
Class.forName(driver).newInstance();
conn = DriverManager.getConnection(url+dbName,userName,pa ssword);
System.out.println("Connected to the database");
} catch (Exception e) {
e.printStackTrace();
}

//CREATE TABLE
try
{
String table = "CREATE TABLE CREDIT(Amount integer)";
Statement st = conn.createStatement();
st.executeUpdate(table);
System.out.println("Table creation process successfully!");
}
catch(SQLException s){
System.out.println("Table all ready exists!");
}

//SELECT
try{
conn.setAutoCommit(false);
Statement st = conn.createStatement();
String sqlRetrieveAmount = "select * from CREDIT";
ResultSet Result = null;
Result = st.executeQuery(sqlRetrieveAmount);
int Amount=10;
System.out.println("Amount:");
while (Result.next()) {
//System.out.print(Result.getInt(1));
Amount=Result.getInt(1);
}
System.out.print(Amount);
System.out.println("");
Result.close();
} catch (Exception e1) {
e1.printStackTrace();
}

//SELECT-UPDATE
try{
conn.setAutoCommit(false);
Statement st = conn.createStatement();
String sqlRetrieveAmount = "select * from CREDIT";
int Amount=0;
int UpdatedAmount=0;
ResultSet Result = null;
Result = st.executeQuery(sqlRetrieveAmount);

System.out.println("Amount:");
while (Result.next())
{
Amount=Result.getInt(1);
}
UpdatedAmount=Amount+40;
System.out.print(Amount);
String sqlUpdateDb = "update CREDIT set Amount="+UpdatedAmount;
st.executeUpdate(sqlUpdateDb);
System.out.println("\nUpdatedAmount");
System.out.print(UpdatedAmount);

Result = st.executeQuery(sqlRetrieveAmount);
System.out.println("\nNow the Amount is:");
while (Result.next()) {
Amount=Result.getInt(1);
}
System.out.print(Amount);
Result.close();

System.out.println("Table updated.");
} catch (Exception e) {
e.printStackTrace();
}

//DISCONNECT
try {
conn.close();
System.out.println("Disconnected from database");
} catch (Exception e) {
e.printStackTrace();
}




}
}

Netbeans Output (Same every time. WHY? )

MySQL Connect Example.
Connected to the database
Table all ready exists!
Amount:
0
Amount:
0
UpdatedAmount
40
Now the Amount is:
40Table updated.
Disconnected from database

[masijade]

You call

conn.setAutoCommit(false);

and then never call

conn.commit()

nor do you call

conn.rollback()

after exceptions. So, of course there is no data, you are discarding it by not commiting it. Nor are you guaranteeing that nothing that "half-way succeeds" is removed in case of an error.

[esgol]

when shall i call

conn.commit()
or
conn.rollback()

after

st.executeUpdate(sqlUpdateDb);

perhaps?

Thank you

[doWhile]

See the examples here: Using Transactions (The Java™ Tutorials > JDBC(TM) Database Access > JDBC Basics)

[esgol]

THAAAANKS!!! WITH CONN.COMMIT(); TI WOOOORKSSSSS!!!!!! OMGGGG!!!!!!

F***** EXAMPLEDEPOSIT.COM examples!!! How could not have it?!!! ( or i missed it )