I'm relatively new to coding and Java. I have an assignment where we build a GUI using JavaFX that interfaces with an oracle database with relevant data to be entered into our GUI product. In our GUI we are supposed to have an Update button which function is to update/alter a specific row in the database after making changes to the data in the GUI textfields/comboboxes. For my update action I have the button linked to I get the error java.sql.SQLSyntaxErrorException: ORA-01729: database link name expected. I have searched online for answers but I don't fully understand what this means and how to solve this issue. I set up my connection in the beginning of my code and included static Connection con; Statement stmt; earlier in my code. Any ideas/help would be appreciated
My code is below:
void updateEmp() {
try {
String updateQuery = "UPDATE employees SET firstname = '"
+ tfFirstName.getText() + "', lastname = '"
+ tfLastName.getText() + "', salary = "
+ tfSalary.getText() + ", title = '"
+ jobTitlesCbo.getValue() + "'";
/*if (getDeptNum(deptTitlesCbo.getValue()) > 0
&& getDeptNum(deptTitlesCbo.getValue()) < 6) {
updateQuery = updateQuery + ", departmentid = '"
+ getDeptNum(deptTitlesCbo.getValue()) + "'";
}*/
updateQuery = updateQuery + " WHERE employeeid = " + tfEmpID;
stmt.executeUpdate(updateQuery);
} catch (Exception e) {
System.out.println("Error: " + e.toString());
e.printStackTrace();
}
}
I am working on Java GUI application which connects to SQL database on localhost (I use XAMPP). When I change some entry, for example Age, I click on "Save changes", it is saved and changes are done in SQL database, but when I click on ">" or "<" to view next or previous person and then go back to the person, where I did changes, every entry is without changes in its initial state. But when I close the application and reopen it, all the changes which I made are done. This is part of the code where is mistake, I think. Thank you.
private void jButtonSaveChangesActionPerformed(java.awt.event.ActionEvent evt) {
try {
Statement stmt = con.createStatement();
try {
String query1 = "UPDATE list1 SET " +
"name ='" + jTextFieldName.getText() + "', " +
"surname ='" + jTextFieldSurname.getText() + "', " +
"age ='" + jTextFieldAge.getText() + "' " +
"WHERE ID = " + jLabelActualID.getText();
stmt.executeUpdate(query1);
} catch (Exception e) {
System.err.println(e);
}
} catch (Exception e) {
System.err.println(e);
}
}
Picture of application:
You are not closing, which can be done more safe and automatically with try-with-resources.
This means a commit might not have happened yet. There is an autocommit setting too.
String query1 = "UPDATE list1 SET " +
"name = ?, " +
"surname = ?, " +
"age = ? " +
"WHERE ID = ?";
try (PreparedStatement stmt = con.prepareStatement(query1)) { // Closes stmt.
stmt.setString(1, jTextFieldName.getText());
stmt.setString(2, jTextFieldSurname.getText());
stmt.setInt(3, Integer.parseInt(jTextFieldAge.getText()));
stmt.setString(4, jLabelActualID.getText());
int updateCount = stmt.executeUpdate();
} catch (SQLException | NumberFormatException e) {
System.err.println(e);
}
The same may hold (or may not hold) for the SQL connection.
Also one should use a PreparedStatement for security (SQL injection) and type safeness / escaping of backslash, quote in strings. As you see it is even more readable.
Another case is a second application accessing the database: it can use its own cache, thereby be a bit outdated.
I'm using twitter4j's streaming API to collect tweets. I'm doing this on java platform. I'm getting a stream of tweets at console but can't store.
public void onStatus(Status status) {
try
{
String myDriver = "org.gjt.mm.mysql.Driver";
String myUrl = "jdbc:mysql://localhost/twitterapi";
Class.forName(myDriver);
Connection conn = DriverManager.getConnection(myUrl, "twitterapi", "");
String query = " insert into tweets"
+ "(tweet_id,tweet_text,screen_name)" + " values"
+ "('" + status.getId() + "','" +
status.getText() + "', '" +
status.getUser().getScreenName() +"')";
Statement statement = conn.createStatement();
statement.executeUpdate(query);
conn.close();
}
catch (Exception e)
{
System.err.println("Got an exception!");
System.err.println(e.getMessage());
}
System.out.println("onStatus #" + status.getUser().getScreenName() + " - " + status.getText());
}
Please consider every other thing to be correct since that's already working.
In your insert you have a different number of columns to values. You are not specifying the author_id.
In addition, as DaveH noticed, you're not actually running the SQL command against the server.
I have a JDBC ResultSet that gives me a TimeOut after only a few thousand rows are processed. I have a few million rows to process, so I'd like to tweak my program to avoid this, just not sure what needs to be tweaked.
Database table is indexed and returns data quickly using selection criteria, so I don't believe it is on the database side. I'm returned 14 columns mixed between address columns and ints. Not a lot of data.
I'm doing a connection.createStatement() and then building the SQL from there. The answer might be I should use a prepared statement.
Statement stmt = null;
ResultSet rs = null;
try {
stmt = conn.createStatement();
String jobNameFilter = (Cli.getJobName() != null) ? " AND [JobName] = '" + Cli.getJobName() + "'" : "";
String sortOrder = (Cli.isAscending()) ? "ASC" : "DESC";
String orderByClause = Cli.isRandom() ? " ORDER BY [Randomizer] " + sortOrder + ",[RecordID] " + sortOrder : " ORDER BY [RecordID] " + sortOrder;
String startingIdFilter = (Cli.getStartingId() != null) ? " AND [RecordId] > " + Cli.getStartingId() : "";
String driverQuery = "SELECT [RecordID], [Column1] AS [TrackingID], [Address]" + ", [Suite] AS [AptSuiteOther], [City], [Building2Key]"
+ ", [ST] AS [State], [ZIPCode]" + ", [BusinessName], [ContactLastName], [Suite]" + ", [Phone], [EmailAddress]"
+ " FROM [Project].[TestSet] WITH (READUNCOMMITTED)"
+ " INNER JOIN [Project].[State] sttable ON sttable.[ST] = UPPER([Project].[TestSet].[ST]) AND [TerritoryFlag] = 0" + " WHERE [BuildingKey] = 0 " + jobNameFilter
+ startingIdFilter + " AND (([FirstResponse] IS NULL AND ([Building2Key] IS NULL OR [Building2Key] = 0)) OR ([Building2Key] > 0 AND [SecondResponse] IS NULL)) " + orderByClause;
rs = stmt.executeQuery(driverQuery);
} catch (SQLException e1) {
logger.error("SQLException", e1);
}
try {
while (rs.next()) {
int recordId = rs.getInt("RecordID");
// Process data
numberProcessed++;
}
} catch (SQLException sqle) {
logger.error("SQLException", sqle);
}
I'm closing all the ResultSet, Connection and Statement in a finally statement at a different level also.
I'm not sure if I need to set the timeout to something higher, setFetchSize to something greater? Trap timeout and create ResultSet again?
Change logic to only pull one row at a time?
You'd have to profile your app to find out for sure, but I'm guessing that the "// Process data" part is the culprit. You're holding the connection open while process all of the rows.
I'd suggest that you read a batch of rows at a time, close the statement, and then process the batch. Then do a select for the next batch, rinse and repeat.
Selecting one row at a time would introduce a lot of overhead, so I wouldn't suggest doing that.
Also, make sure that you're using a connection pool, so that you don't actually have to build a new Connection each time. The pool will keep it open for you, and recycle it if it goes dead / times out.
I have a table A. I insert data into table A through a user interface. Table A has an ID(primary key), which is generated using a sequence, and 16 other columns. One of the column is called cntrct_no.
When I try to insert data into the table through UI, it works fine the first time. I check the table A and all the data are there.
But when I try to insert the same data again without changing anything, it looks like the data is getting added to the table and I do not get any errors. But when I check table A, the data inserted the second time is not there.
If I try to insert the same data directly thorough SQL developer, the data gets inserted into the table.
The weird thing is if I just change the value of the cntrct_no in the UI and leave rest of the data same, the data gets inserted.
Can anyone please explain to me what could possibly cause this?
Not sure if this helps: stmt.executeUpdate(); returns 0 when the data is not inserted and a 1 when it's inserted.
public void writeToAudit(String contractNo, String tripNo,
String tripEffDate,
String tripDiscDate, String transpModeId, String userId,
String transType, AplLeg[] legs) {
final Session session = HibernateUtil.getSession();
Connection con = null;
con = session.connection();
PreparedStatement stmt = null;
PreparedStatement stmtSelId = null;
ResultSet rs = null;
long nextId = -1;
int i=0;
try {
for(i=0;i<legs.length;i++) {
String sqlNextId = "SELECT rpt_audit_transportation_seq.NEXTVAL as seqval FROM DUAL";
stmtSelId = con.prepareStatement(sqlNextId, ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_UPDATABLE);
rs = stmtSelId.executeQuery();
rs.last();
final int rows = rs.getRow();
if (rows == 0){
nextId = -1;
}
rs.beforeFirst();
rs.next();
nextId = rs.getInt(1);
if(nextId==-1)
throw new SQLException("Cannot get next val from rpt_audit_transportation sequence.");
stmt = con.prepareStatement(WRITE_TO_AUDIT_DML);
stmt.setLong(1, nextId);
stmt.setString(2, userId.toUpperCase());
stmt.setString(3, transType);
stmt.setString(4, contractNo);
stmt.setString(5, tripNo);
stmt.setInt(6, Integer.parseInt(transpModeId));
stmt.setString(7, tripEffDate);
stmt.setString(8, tripDiscDate);
stmt.setLong(9, legs[i].getLegId().longValue());
int temp = stmt.executeUpdate();
con.commit();
}
stmt.close();
}
catch (Exception e) {
}
finally {
closeConnection(session, con, stmtSelId, rs);
}
}
THE SQL STATEMENT:
private static final String WRITE_TO_AUDIT_DML =
"INSERT INTO rpt_audit_transportation " +
"(audit_id, audit_date, audit_process, audit_userid, " +
"audit_trans_type, audit_route_no, audit_trip_no, " +
"audit_eff_dt, audit_disc_dt, audit_orig_facility_id, " +
"audit_dest_facility_id, audit_arvl_tm, audit_dprt_tm, " +
"audit_leg_seq_no, audit_freq_id, audit_trnsp_mode_id) " +
"(SELECT ?, " + // audit id
"SYSDATE, " +
"'TOPS_UI', " +
"?, " + // userId
"?, " +
"rte.cntrct_no, " +
"trp.trip_no, " +
"rte.cntrct_eff_dt, " +
"rte.cntrct_disc_dt, " +
"NVL(leg.orig_facility_id, trp.orig_fac_id), " +
"NVL(leg.dest_facility_id, trp.dest_fac_id), " +
"NVL(leg.arvl_tm, trp.arvl_tm), " +
"NVL(leg.dprt_tm, trp.dprt_tm), " +
"leg.leg_seq, " +
"trp.freq_id, " +
"rte.trnsp_mode_id " +
"FROM apl_contract rte, " +
"apl_trip trp, " +
"apl_leg leg " +
"WHERE rte.cntrct_no = ? " + // contract id
"AND trp.trip_no = ? " + // trip no
"AND rte.trnsp_mode_id = ? " + // transp mode id
"AND rte.cntrct_locked_ind = 'N' " +
"AND trp.trip_eff_dt = to_date(?,'MM/DD/YYYY') " + // trip eff date
"AND trp.trip_disc_dt = to_date(?,'MM/DD/YYYY') " + // trip disc date
"AND trp.cntrct_id = rte.cntrct_id " +
"AND leg.trip_id = trp.trip_id " +
"AND leg.leg_id = ?) ";
Looks like you're not inserting plain values, but a result of a select based on the parameters.
What you are using is an INSERT ... SELECT () clause, so if the SELECT part does not return any rows, the INSERT won't insert anything, and stmt.executeUpdate() will return 0. Find out why SELECT returns no rows.
This may be due some triggers saving stuff in other tables when you do the insert into rpt_audit_transportation, but it's just a guess.
The problem is that you have a catch that is swallowing your exceptions
catch (Exception e) {
}
That means that when the SQL statement throws an error, you're telling your code to catch the exception and ignore it. It is almost always an error to do that since, as you're discovering, it means that your code can fail to do what you expect with no way of letting you know that something failed. At a minimum, you would need to log the exception somewhere. In general, though, if you cannot fix whatever condition lead to the exception, you ought to re-raise the exception or simply not catch it in the first place.
My guess is that the second insert is violating some constraint defined on the table. But since your code is catching the exception and throwing it away, you're not being notified that there was a constraint violation nor is your code noting which constraint was violated.
When the cntrct_no is same you are getting an exception and you are supperessing that as told by #Justin Cave. This may be because you are having a unique constraint for that field and the DB throws an error and you are suppressing.
When cntrct_no is changed - obviously the constraint wont fail and for primary key since you are using the sequence it would have generated the next number and it happily gets inserted in the DB.
Don't ever suppress the exception. Do some thing in that block either rethrow as application specific exception or convert to error code and propagate that to the front end.