In my program I execute some SQL queries with JDBC. When I run the program for this certain query I get the following error:
SQLException: Exception in thread "main" java.sql.SQLException:at TransformData.main(TransformData.java:213)
Here is this part of code:
try
{
dbcon = DriverManager.getConnection(url,"username","password");
stmt = dbcon.createStatement();
stmt1 = dbcon.createStatement();
stmt13 = dbcon.createStatement();
stmt14 = dbcon.createStatement();
String sql1 = "SELECT DISTINCT payer_id FROM transactions ORDER BY payer_id";
rs1 = stmt1.executeQuery(sql1);
while (rs1.next())
{
Integer payer_id = rs1.getInt("payer_id");
payer_ids.add(payer_id);
}
rs1.close();
stmt1.close();
for(int i = 0; i < payer_ids.size(); i++)
{
String sql13 = "SELECT COUNT(*) AS counter, isCOrporate FROM transformed_table WHERE payer_id = "+payer_ids.get(i)+" ";
rs5 = stmt13.executeQuery(sql13);
while(rs5.next())
{
int counter = rs5.getInt("counter");
int isCorporate = rs5.getInt("isCorporate");
if ((counter - payer_ids.get(i).intValue() - isCorporate) < 1)
{
String sql14 = "DELETE FROM transformed_table WHERE payer_id = "+payer_ids.get(i)+" ";
stmt14.executeUpdate(sql14);
}
}
}
rs5.close();
stmt13.close();
stmt14.close();
dbcon.close();
}
catch(SQLException e)
{
System.out.print("SQLException: ");
throw new SQLException(errorMessages);
}
Line 213 is this line: throw new SQLException(errorMessages); in catch.
I am trying to find what might throw this exception. Can someone help?
There are lots of things wrong with this code, but here's the pertinent hint: Your catch block is wrong. Write it this way:
catch(SQLException e) {
e.printStackTrace();
}
Your way drains all the useful information out of the stack trace. You can't debug what else you've done wrong.
Make the change, rerun the code, and read the stack trace. It'll tell you what your real problem is.
So many things to correct:
Resources aren't closed properly. Those should be done in individual try/catch blocks in a finally block.
Badly written SQL. The DELETE could be done far more efficiently with a JOIN.
Poor decomposition. There are 2 or 3 methods hiding in here.
No transaction manager; no ACID.
No connection pooling; should be passed into this method rather than instantiated in scope.
Should use PreparedStatement and binding rather than concatenating String.
I'm not certain, but it looks like you have three SQL queries:
SELECT all the payer IDs
Get a COUNT of payer IDs
DELETE all the payer IDs in the list you got from SELECT.
Do I read that correctly? If yes, why don't you do it in one query, like this?
DELETE
FROM transformed_table
WHERE payer_id IN (SELECT DISTINCT payer_id FROM transactions)
Related
It Takes Too Long For Me To Create And Send PreparedStatement's or ResultSet.
How Can I Get MaxID From SQL in Java Method?
Writed this but not working...
private static int getLastId()
{
int returned=0;
try
{
PreparedStatement stat;
ResultSet rs;
String sql="select max(id) from home";
stat=conn.prepareStatement(sql);
rs=stat.executeQuery();
while(rs.next())
{
returned = rs.getInt("id")+1;// just want a new id for new person
}
}
catch (Exception e)
{
System.out.println(""+e);
}
return returned;
}
I Tried To Use It Like This...
//reseting every thing and get lastId+1;
System.out.println("added");
field_name.setText("");
field_pass.setText("");
int temp= getLastId();
field_id.setText(""+temp);
But It Returns 0!
I Don't Have any SQL error.
Did I Use It Wrong?
or ?
Thanks For Help.
You have a few problems here, one of which is that in your current code you aren't actually accessing the max(id) which you put in the query. One way around this is to assign an alias:
PreparedStatement stat;
ResultSet rs;
String sql = "SELECT MAX(id) AS max_id FROM home";
stat = conn.prepareStatement(sql);
rs = stat.executeQuery();
if (rs.next()) {
returned = rs.getInt("max_id") + 1;
}
This fixes the syntax problem, but there is still the problem of whether this is the best way to get the next id. I would recommend that you switch to using an auto increment column, which MySQL will manage for you. Then, you don't need to worry about keeping track of the latest ID value. In fact, you don't even need to specify a value when inserting; the database will handle this for you.
I'm writing data from Java to an Access database on Windows 32 bit. When I write a record, I need to retrieve the row ID / primary key so that I can a) update the record easily if I want to and b) cross reference other data to that record.
When did something similar in C, I could make a updatable cursor which allowed me to write a new record and simultaneously retrieve the row ID. With Java, it looks as though I should be able to do this, but it throws an exception with the following code.
con = openAccessDatabase();
String selectString = "SELECT ID, RunCount FROM SpeedTable";
try {
PreparedStatement selectStatement = con.prepareStatement(selectString,
ResultSet.TYPE_SCROLL_INSENSITIVE,
ResultSet.CONCUR_UPDATABLE);
ResultSet idResult = selectStatement.executeQuery();
int id;
for (int i = 0; i < nWrites; i++) {
idResult.moveToInsertRow();
idResult.updateObject(1, null); // this line makes no difference whatsoever !
idResult.updateInt(2, i);
idResult.insertRow(); // throws java.sql.SQLException: [Microsoft][ODBC Microsoft Access Driver]Error in row
id = idResult.getInt(1);
}
selectStatement.close();
} catch (SQLException e) {
e.printStackTrace();
}
The only thing I've been able to do is to write a new record and then run a different query to get the Row id back ...
String insertString = "INSERT INTO SpeedTable (RunCount) VALUES (?)";
String idString = "SELECT ID FROM SpeedTable ORDER BY ID DESC";
//
try {
ResultSet idResult = null;
PreparedStatement preparedStatement, idStatement;
preparedStatement = con.prepareStatement(insertString,
ResultSet.TYPE_FORWARD_ONLY,
ResultSet.CONCUR_READ_ONLY);
idStatement = con.prepareStatement(idString,
ResultSet.TYPE_FORWARD_ONLY,
ResultSet.CONCUR_READ_ONLY);
for (int i = 0; i < nWrites; i++) {
// write the data into the database
preparedStatement.setInt(1, i);
preparedStatement.execute();
// re-run the query to get the index back from the database.
idResult = idStatement.executeQuery();
idResult.next();
int lastIndex = idResult.getInt(1);
idResult.close();
}
This works but becomes impossibly slow when the table has more than a few 10's of 1000's of records in it. There is also a risk of returning the wrong ID if two parts of the program start writing at the same time (unlikely but not impossible).
I know that at least one suggestion will be to either not use Java or not use Access, but they are not options. It's also part of a free open source software package, so I'm reluctant to pay for anything. Writing my own C JNI interface which provides the basic functionality that I need for my application is even less appealing.
Not sure if this works for MS Access but you can try:
st.executeUpdate("INSERT INTO SpeedTable (RunCount) VALUES (1000)", Statement.RETURN_GENERATED_KEYS);
ResultSet rs = st.getGeneratedKeys();
rs.next();
long id = rs.getLong(1);
My JAVA script consists of 2 JAVA classes: RMS, queryRMS
In the RMS class I call the method in the queryRMS class
RMS Java Class (I left out the start execution part, below is just the method)
for (int i = 1; i <= itemCount; i++) {
GlobalVariables.numberRow = i;
JavaDatapool.settings();
String item = queryRPM.connectDB_Multi(configFile,"SELECT ITEM FROM ORDSKU WHERE ORDER_NO = '" + orderNo + "' ORDER BY ITEM ASC",i);
JavaDatapool.writeXLS("item",item,GlobalVariables.sheetXLS);
sleep(1);
}
queryRMS JAVA class
public static String connectDB_Multi(String configFile, String query, int i) throws FileNotFoundException, IOException, SQLException, ClassNotFoundException{
Properties p = new Properties();
p.load(new FileInputStream(configFile));
String serverName = (p.getProperty("RMS_DBServerName"));
String portNumber = (p.getProperty("RMS_PortNumber"));
String sid = (p.getProperty("RMS_SID"));
String url = "jdbc:oracle:thin:#//" + serverName + ":" + portNumber + "/" + sid;
String username = (p.getProperty("RMS_Username"));
String password = (p.getProperty("RMS_Password"));
// jdbc:oracle:thin:#//localhost:1521/orcl
Class.forName("oracle.jdbc.driver.OracleDriver");
Connection connection = DriverManager.getConnection(url,username,password);
String setr = null;
try {
Statement stmt = connection.createStatement();
try {ResultSet rset = stmt.executeQuery(query);
try {
while(rset.absolute(i))
setr = rset.getString(1);
return setr;
}
finally {
try { rset.close();
}
catch (Exception ignore) {}
}
}
finally {
try { stmt.close();
}
catch (Exception ignore) {}
}
}
finally {
try { connection.close();
}
catch (Exception ignore) {}
}
}
So what it does is call the connectDB_multi class and then returns the String where the next part is saving it inside an Excel worksheet.
The loop should return all rows, one at a time and then save it inside the Excel worksheet.
In the second time in loop the query is faulted, eventhough the query should return 1 column consisting of 2 rows.
the original contained the part while(rset.next()) instead of while(rset.absolute(i))
but next only return the first row everytime. so the script works when only one column and row is retrieved from the Database.
Your logic looks a bit messed up.
Look at the first loop you posted. You are, effectivly, executing:
SELECT ITEM FROM ORDSKU WHERE ORDER_NO = '" + orderNo + "' ORDER BY ITEM ASC
itemCount number of times. Each time you execute it, you are attempting to access the n:th row, n being loop counter. Do you see a problem there? How do you know that the query will return itemCount number of rows? Because if it doesn't, it will fail since you are attempting to access a row that doesn't exist.
What I suspect you WANT to do is something like this
Statement stmt = connection.createStatement();
ResultSet rset = stmt.executeQuery(query);
while(rset.next()) {
JavaDatapool.writeXLS("item",rset.getString(1),GlobalVariables.sheetXLS);
}
You should also seriously consider using some form of connection pooling to avoid having to re-open new connections all the time as that is a pretty time-consuming operation.
This code seems very inefficient, for each row you want to fetch from the database you read a property file, create a connection, select all matching rows, skip ahead to the row you want and return just that row. (Or at least I think that is what you are trying to do).
Your code
while(rset.absolute(i))
setr = rset.getString(1);
is probably an infinite loop as it will continue to go to the same row as long as it is ok to go to that row, so either that row does not exist (and the while exists) or the row does exist (and while continues forever).
You should probably restructure your program to only do one select and read all rows that you want and store them in your excel file. While doing this, you can debug to see if you actually are getting the data you expect.
Apart from the inefficient code of creating new connections and querying once for each row, how do you know how many rows you want?
I think in the end you want something like this
....
while(rset.next()) {
JavaDatapool.writeXLS("item",item,GlobalVariables.sheetXLS);
}
And what is the sleep(1) support to accomplish?
FYI: if you open and close statement too often as your logic or pap's solution, you can get the " java.sql.SQLException: ORA-01000: maximum open cursors exceeded" error message.
I suggest you to not do 'too much generalize'. I saw a lot of OOP programmers overdid generalization and that is painful. You should design by a goal and the goal should not be 'just alignment' nor 'code look beautiful', it has to have a purpose for designing.
I have following code:
public boolean updateDatabase(long houseValue, List<Users> userList)
{
boolean result = false;
Connection conn = null;
PreparedStatement stmtUpdateUsers = null;
PreparedStatement stmtQueryHouse = null;
PreparedStatement stmtUpdateHouse = null;
ResultSet rs = null;
String updateUsers = "UPDATE users SET money = ? WHERE username = ?";
String queryHouse = "SELECT * FROM house WHERE house_id = ?";
String updateHouse = "UPDATE house SET house_money = ? WHERE house_id = ?";
try
{
conn = getConnectionPool().getConnection();
conn.setAutoCommit(false);
stmtUpdateUsers = conn.prepareStatement(updateUsers);
...
// Here is some code that updates Users table in a short loop
...
stmtQueryHouse = conn.prepareStatement(queryHouse);
stmtQueryHouse.setInt(1, 1);
rs = stmtQueryHouse.executeQuery();
if(rs.next())
{
long houseMoney = rs.getLong("house_money");
houseMoney += houseValue;
stmtUpdateHouse = conn.prepareStatement(updateHouse);
stmtUpdateHouse.setLong(1, houseMoney);
stmtUpdateHouse.setInt(2, 1);
stmtUpdateHouse.executeUpdate();
}
else
{
throw new SQLException("Failed to update house: unable to query house table");
}
conn.commit();
result = true;
}
catch(SQLException e)
{
logger.warn(getStackTrace(e));
try{conn.rollback();}catch(SQLException excep)
{
logger.warn(getStackTrace(excep));
}
}
finally
{
DbUtils.closeQuietly(rs);
DbUtils.closeQuietly(stmtQueryHouse);
DbUtils.closeQuietly(stmtUpdateUsers);
DbUtils.closeQuietly(stmtUpdateHouse);
try { conn.setAutoCommit(true); } catch (SQLException e) { /* quiet */ }
DbUtils.closeQuietly(conn);
}
return result
}
This method can be called from multiple threads, house table is just a one row table which holds total earned money. It gets updated by different threads.
Problem is that stmtQueryHouse.executeQuery() returns empty set, and it should not happen, because house table always have (since database creation) one single row that gets updated (only house_money column is updated).
When I run this code on windows (JDBC driver + mysql 5.5.13) it works fine, but when I run it on CentOS (same JDBC driver + mysql 5.1.57) it returns empty result set very often (if not always). Any idea what is going wrong or how could I check where is the problem? Maybe I should use select for update, but then why it works on windows and not on linux? I appreciate any help. Thanks in advance.
Look in the mysql general query log for any errors?
I realize this isnt your question per se, but if you have another table with just a single row for each House, it sounds to me that it would make more sense to move house_money into your main house table
I'd say this one method is doing far too much.
I'd pass in the Connection to three separate methods and manage the transaction outside all of them.
I'd wonder if there's an optimization that would eliminate one of the UPDATES.
I'd want to batch all these so I didn't do a round trip for each and every user. It'll perform poorly as the # of users increases.
This question already has answers here:
ResultSet exception - before start of result set
(6 answers)
Closed 5 years ago.
try
{
PreparedStatement s = (PreparedStatement) conn.prepareStatement("SELECT voters.Check,count(*) FROM voting.voters where FirstName="+first+"and LastName="+last+" and SSN="+voter_ID);
//java.sql.Statement k = conn.createStatement();
rs=s.executeQuery();
//s.executeQuery("SELECT voters.Check,count(*) FROM voting.voters where FirstName="+first+"and LastName="+last+" and SSN="+voter_ID);
System.out.println(rs.first());
c=rs.getInt(1);
d=rs.getInt(2);
System.out.println(c);
System.out.println(d);
if(c==1 && d==1)
{
s.executeUpdate("update cand set total=total+1 where ssn="+can_ID);
System.out.println("Succeful vote");
System.out.println("after vote");
s.executeUpdate("update voters set voters.Check=1 where ssn="+voter_ID);
toclient=1;
PreparedStatement qw = (PreparedStatement) conn.prepareStatement("select FirstName from cand where ssn="+can_ID);
// rs=k.executeQuery("select FirstName from cand where ssn="+can_ID);
rs1 = qw.executeQuery();//Error Here Plz help me
String name1= (String) rs1.getString(1);
System.out.println(name1);
s.executeUpdate("update voters set VTO="+name1+"where ssn="+voter_ID);
System.out.println(rs.getString(1));
}
else
{
if(c != -1)
toclient =2;
if( d ==0)
toclient =3;
if( d>1)
toclient =4;
}
System.out.println("out-----------");
rs.close();
s.close();
}
catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
Error IS :
java.sql.SQLException: Before start of result set
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1072)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:986)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:981)
The common practice is to use rs.next() method with while cycle:
PreparedStatement st = conn.prepareStatement("select 1 from mytable");
ResultSet rs = st.executeQuery();
while (rs.next()) {
// do something with result set
}
rs.close();
st.close();
I've omitted try/catch/finally clauses for clarity. Note that you should invoke each close() method in separate finally block.
While rs1.first() may work, to avoid exception I would like to avoid it and use rs1.next() instead.
See javadoc of ResultSet.first():
SQLException - if a database access error occurs; this method is called on a closed result set or the result set type is TYPE_FORWARD_ONLY
SQLFeatureNotSupportedException - if the JDBC driver does not support this method
while next doesn't have this limitation
Code:
if (rs1.next()) {
String name1 = rs1.getString(1);
}
Tips: avoid useless type casting (your code is full of them)
In your code snippet you create PreparedStatements but you do not use them correctly. Prepared statements are meant to be used as a kind of 'statement template' which is bound to values before it executes. To quote the javadoc:
PreparedStatement pstmt = con.prepareStatement(
"UPDATE EMPLOYEES SET SALARY = ? WHERE ID = ?");
pstmt.setBigDecimal(1, 153833.00)
pstmt.setInt(2, 110592)
This has two big advantages over your current usage of PreparedStatement:
one PreparedStatement can be used for multiple executes
it prevents a possible SQL injection attack
The second one here is the biggie, if for instance your variables first and last are collected in a user interface and not reformatted, you run the risk of parts of SQL being input for those values, which then end up in your statements! Using bound parameters they will just be used as values, not part of the SQL statement.
When you get a resultset, the cursor is placed before the first row. Trying to get anything before moving your cursor to the first row will cause the error you received. You need to move the cursor to the first row using this line:
rs1.first();
before calling
String name1 = (String) rs1.getString(1);
Of course, make sure the resultset contains entries before calling rs1.getString(1).
Call rs1.first() before using the ResultSet.
Moves the cursor to the first row in this ResultSet object.
Initially the cursor position of the ResultSet is before the start of the set. The first() method returns true if there is data in the set. So preferably:
if (rs1.first()) {
String name1 = (String) rs1.getString(1);
}
So, to be sure the proper use of PreparedStatment, here is your original example adjusted for best practices (note the cast is redundant):
PreparedStatement s = conn.prepareStatement(
"SELECT voters.Check,count(*) " +
"FROM voting.voters " +
"where FirstName=? and LastName=? and SSN=?");
s.setString(1,first);
s.setString(2,last);
s.setString(3,voter_ID);
ResultSet rs = s.executeQuery();
while( rs.next() ) {
c = rs.getInt(1);
d = rs.getInt(2);
}
Hope this helps... :)