We Keep Coding

Looping try/catch statement

I'm trying to take two random rowid from my database. Everything works but I have a scenario when there is only one rowid. I want to make a loop on my try/catch until there is second number in my database.
What I'm doing wrong? Thank you
public void Kaslaimejo() {
String sql = "SELECT rowid FROM Zaidejai WHERE Pirmas < 4 ORDER BY random() LIMIT 2";
Integer value1 = null, value2 = null;
Integer judesiukas1 = null, judesiukas2 = null;
int a = 0;
int k = 15; // kiek kartu? Reikia infinity padaryti
for (a = 0; a < 3; a++) {
try {
Connection conn = Serveris.connect();
Statement stmt = conn.createStatement();
ResultSet rs = stmt.executeQuery(sql)) {
if (rs.next()) {
value1 = rs.getInt("rowid");
if (rs.next()) {
value2 = rs.getInt("rowid");
PreparedStatement buvo = conn.prepareStatement("UPDATE Zaidejai SET Numeriukas = ? WHERE rowid = ?");
buvo.setInt(1, i);
buvo.setInt(2, value1);
int buvolala = buvo.executeUpdate ();
PreparedStatement buvo2 = conn.prepareStatement("UPDATE Zaidejai SET Numeriukas = ? WHERE rowid = ?");
buvo2.setInt(1, i);
buvo2.setInt(2, value2);
int buvolala2 = buvo2.executeUpdate ();//
i++;
}
System.out.println("Pirmas zaidejas" + value1); // atspausdina 1 random zaideja is duomenu bazes
System.out.println("Antras zaidejas" + value2); // atspausdina 2 random zaideja is duomenu bazes
}
} catch (SQLException e) {
a--;
//System.out.println(e.getMessage());
}
}
}
Right now my program loops two times and then gives me SQLException. How I can loop my program until there is no SQLException?

OK, I've tried to write what I think you're trying to do.
You wait for ever until someone puts at least two entries in the database.
You extract two values, process them, then wait some more.
Some points to watch out:
1. Object comparisons need to be made with .equals() not with ==
2. You might want to provide some way to break out of the infinite loop I've written (while(true)).
3. Careful with null values. They might produce NullPointerException.
4. Try to break up your code into methods. Each large block of code could go into each own method.
public void Kaslaimejo(){
String sql = "SELECT rowid FROM Zaidejai WHERE Pirmas < 4 ORDER BY random() LIMIT 2";
Integer judesiukas1 = null, judesiukas2 = null;
while(true) {
List<Integer> values = new ArrayList<>();
while (values.size() < 2) {
try (Connection conn = Serveris.connect();
Statement stmt = conn.createStatement();
ResultSet rs = stmt.executeQuery(sql)) {
if( rs.next() ){
Integer value = rs.getInt("rowid");
values.add(value);
}
} catch (SQLException e) {
e.printStackTrace();
}
}
try( Connection conn = Serveris.connect()) {
PreparedStatement buvo = conn.prepareStatement("UPDATE Zaidejai SET Numeriukas = ? WHERE rowid = ?");
buvo.setInt(1, i);
buvo.setInt(2, values.get(0));
int buvolala = buvo.executeUpdate ();
PreparedStatement buvo2 = conn.prepareStatement("UPDATE Zaidejai SET Numeriukas = ? WHERE rowid = ?");
buvo2.setInt(1, i);
buvo2.setInt(2, values.get(1));
int buvolala2 = buvo2.executeUpdate ();//
i++;
}catch (SQLException e) {
e.printStackTrace();
}
Connection conn = Serveris.connect();
try {
PreparedStatement pstmt = conn.prepareStatement("SELECT Pirmas FROM Zaidejai WHERE rowid = ?");
PreparedStatement pstmt2 = conn.prepareStatement("SELECT Pirmas FROM Zaidejai WHERE rowid = ?");
pstmt.setInt(1, values.get(0));
pstmt2.setInt(1, values.get(1));
ResultSet myrsv = pstmt.executeQuery();
ResultSet myrsv2 = pstmt2.executeQuery();
{
if (myrsv.next()) {
judesiukas1 = myrsv.getInt("Pirmas");
if (myrsv2.next()) {
judesiukas2 = myrsv2.getInt("Pirmas");
}
}
//System.out.println("Pirmo zaidejo veiksmas" + myrsv.getInt("Pirmas"));
//System.out.println("Antro zaidejo veiksmas" + myrsv2.getInt("Pirmas"));
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
if (judesiukas1.equals(judesiukas2)) // careful here. NullPointerException may happen.
{
try {
PreparedStatement laim = conn.prepareStatement("UPDATE Zaidejai SET Rezultatas = ? WHERE rowid = ?"); // ble ble update reikia naudoti , o ne insert into. Insert kai sukuriame nauja kazka tik
PreparedStatement laim2 = conn.prepareStatement("UPDATE Zaidejai SET Rezultatas = ? WHERE rowid = ?");
laim.setString(1, "Lygiosios");
laim.setInt(2, values.get(0));
laim2.setString(1, "Lygiosios");
laim2.setInt(2, values.get(1));
int irasyk = laim.executeUpdate (); // kodel executeupdate, o ne executequery????
int irasyk2 = laim2.executeUpdate (); // kodel executeupdate, o ne executequery????
{
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
System.out.print("Lygiosios");
} else {
// (1) - Rock
// (2) Scissors
// (3) - Paper
switch (values.get(0)){
case 1:
if (judesiukas2 == 2)
System.out.print("Zaidejas 1 wins!");
else
System.out.print("Zaidejas 2 wins!");
break;
case 2:
if (judesiukas2 == 3)
System.out.print("Zaidejas 1 wins!");
else
System.out.print("Zaidejas 2 wins!");
break;
case 3:
if (judesiukas2 == 1)
System.out.print("Zaidejas 1 wins!");
else
System.out.print("Zaidejas 2 wins!");
break;
}
}
try {
conn.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}

The logic becomes easier if you add the values to a list
var values = new ArrayList<Integer>();
while (values.Count < 2) {
try (Connection conn = Serveris.connect();
Statement stmt = conn.createStatement();
ResultSet rs = stmt.executeQuery(sql))
{
while (values.Count < 2 && rs.next()) {
Integer v = rs.getInt("rowid");
values.Add(v);
}
} catch (SQLException e) {
}
}
//TODO: process the values here
The advantage is, that you can retrieve one value at the first database query and the second at a later one or both in the same round and you don't have to keep track of which one of two variables to use.
(Bear with me with the syntax details, I'm not a Java programmer.)

How i can loop my program until there is no SQLException?
Change this (because, it will only allow to loop two times)
for (a = 0; a < 2; a++) {
to
while(true)
Put everything inside while(true), if exception occurred, then it will come out from the while loop. Something similar :
try
{
while(true)
{
...
...
}
...
}
catch(SQLException e)
{
// do somthing
}

APOSTROPHE issue with java and SQL

I have code, where I have single quote or APOSTROPHE in my search
I have database which is having test table and in name column of value is "my'test"
When running
SELECT * from test WHERE name = 'my''test';
this works fine
If I use the same in a Java program I am not getting any error or any result
But If I give the name with only single quote then it works
SELECT * from test WHERE name = 'my'test';
Could you please help me out to understand.
Java code is
Connection con = null;
PreparedStatement prSt = null;
try {
Class.forName("oracle.jdbc.driver.OracleDriver");
con = DriverManager.
getConnection("jdbc:oracle:thin:#localhost:1521:orcl"
,"user","pwd");
String query = "SELECT * from "
+ "WHERE name = ? ";
prSt = con.prepareStatement(query);
String value = "my'mobile";
char content[] = new char[value.length()];
value.getChars(0, value.length(), content, 0);
StringBuffer result = new StringBuffer(content.length + 50);
for (int i = 0; i < content.length; i++) {
if (content[i] == '\'')
{
result.append("\'");
result.append("\'");
}
else
{
result.append(content[i]);
}
}
prSt.setObject(1, result.toString());
int count = prSt.executeUpdate();
System.out.println("===============> "+count);
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
} finally{
try{
if(prSt != null) prSt.close();
if(con != null) con.close();
} catch(Exception ex){}
}

You don't have to escape anything for the parameter of a PreparedStatement
Just use:
prSt = con.prepareStatement(query);
prSt.setString("my'mobile");
Additionally: if you are using a SELECT statement to retrieve data, you need to use executeQuery() not executeUpdate()
ResultSet rs = prst.executeQuery();
while (rs.next())
{
// process the result here
}
You might want to go through the JDBC tutorial before you continue with your project: http://docs.oracle.com/javase/tutorial/jdbc/index.html

SQL database not populating via Java by using execute/addBatch

I currently have a very large file which contains a few million lines of entries, and want them inserted into a database. The connection established from java to SQL works as I have tried inserting the data singularly and it works, however, when I switched to using executeBatch and addBatch, it seems to loop though but not populating anything into my database.
Code is as follows:
import java.io.BufferedReader;
import java.io.FileReader;
import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.DriverManager;
import java.sql.SQLException;
public class fedOrganiser6 {
private static String directory = "C:\\Users\\x\\Desktop\\Files\\";
private static String file = "combined.fed";
private static String mapperValue = "";
public static void main(String[] args) throws Exception {
Connection conn = null;
try {
BufferedReader mapper = new BufferedReader(new FileReader(directory + file));
String dbURL = "jdbc:sqlserver://localhost\\SQLExpress;database=TIMESTAMP_ORGANISER;integratedSecurity=true";
String user = "sa";
String pass = "password";
conn = DriverManager.getConnection(dbURL, user, pass);
if (conn != null) {
DatabaseMetaData dm = (DatabaseMetaData) conn.getMetaData();
System.out.println("Driver name: " + dm.getDriverName());
System.out.println("Driver version: " + dm.getDriverVersion());
System.out.println("Product name: " + dm.getDatabaseProductName());
System.out.println("Product version: " + dm.getDatabaseProductVersion());
System.out.println("clearing database");
conn.createStatement().executeUpdate("truncate table TimestampsStorage");
System.out.println("bulk insert into database");
System.out.println("complete");
int i = 0;
int records = 0;
String query = "INSERT INTO TimestampsStorage " + "values(" + "'" + mapperValue.toString() + "'"+ ")";
conn.prepareStatement(query);
for (mapperValue = mapper.readLine(); mapperValue != null; mapperValue = mapper.readLine()) {
i++;
records++;
System.out.println("Batching " + records + " records...");
conn.createStatement().addBatch(query);
if (i == 100000) {
conn.createStatement().executeBatch();
i = 0;
}
}
}
conn.createStatement().executeBatch();
conn.createStatement().close();
System.out.print("Done");
} catch (SQLException ex) {
ex.printStackTrace();
} finally {
try {
if (conn != null && !conn.isClosed()) {
conn.close();
}
} catch (SQLException ex) {
ex.printStackTrace();
}
}
}
}

createStatement() creates a new statement object, so you're execute a different statement than the one you're batching on. You should create the PreparedStatement once, add several batches to it, and then execute on the same object:
String query = "INSERT INTO TimestampsStorage VALUES (?)";
PreparedStatement ps = conn.prepareStatement(query);
for (mapperValue = mapper.readLine();
mapperValue != null;
mapperValue = mapper.readLine()) {
i++;
records++;
System.out.println("Batching " + records + " records...");
ps.setString(1, mapperValue);
ps.addBatch();
if (i == 100000) {
ps.executeBatch();
i = 0;
}
}

I think you are a bit mistaken on how batch processing for JDBC works.
You are creating a new Statement each time you call conn.createStatement().
Instead, you will want to use a PreparedStatement. First, change your query to include a ? where you want your values to go.
String query = "INSERT INTO TimestampsStorage VALUES(?)";
Then, when you call conn.prepareStatement(query), store the returned PreparedStatement.
PreparedStatement ps = conn.prepareStatement(query);
This PreparedStatement will then 'remember' your query, and you can simply change the values you want where the ? is on each iteration of your loop.
ps.setString(1, mapperValue);
The setString method will take your mapperValue and use it instead of the first ? it finds in your query (since you pass in the index 1).
Then, instead of calling conn.createStatement().addBatch(), you would call ps.addBatch().
Then, outside of your loop, you can call ps.executeBatch(). (There is no need to call this inside your loop, so you can remove your if (i == 100000) condition).
Finally, if you are using Java 7+, you can use a try with resources, so that you don't need to worry about closing the PreparedStatement or Connection in a finally block.
Here is what your end result should look like.
String query = "INSERT INTO TimestampsStorage VALUES (?)";
try (Connection con = DriverManager.getConnection(dbURL, user, pass); PreparedStatement ps = con.prepareStatement(query);) {
for (mapperValue = mapper.readLine(); mapperValue != null; mapperValue = mapper.readLine()) {
records++;
ps.setString(1, mapperValue);
ps.addBatch();
}
System.out.println("Executing batch of " + records + " records...");
ps.executeBatch();
} catch (SQLException ex) {
//handle exception
}

you are throwing away the prepared statement
String query = "INSERT INTO TimestampsStorage VALUES (?)";
PreparedStatement statement = conn.prepareStatement(query);
for (mapperValue = mapper.readLine(); mapperValue != null; mapperValue = mapper.readLine()) {
i++;
records++;
System.out.println("Batching " + records + " records...");
statement.setString(1,mapperValue);
statement.addBatch();
if (i == 100000) {
statement.executeBatch();
i = 0;
}

Search a JTable using multiple JTextfield

I have a JFrame that has 3 JTextfields and 2 JDatechooser, what I am trying to do is if only one JTextfield has something typed in it and I press the search button, then I will be able to retrieve the data to JTable, but the problem is I have to fill out all JTextFileds and JDatechooser in order to retrieve data. My idea is to ignore null JTextfields and JTdatechooser if only one JTextfield has the keyword I want ?? Any suggestions ?? Thanks in advance,
public ArrayList<BillsRecord> getBillRecordByID(int EmpCode, String Fname, String Lname, String sDate, String eDate) throws SQLException {
String sql = "SELECT B.DATE AS DT, B.EMP_ID, E.FNAME, E.LNAME, MONEY_SENT, RENT, PHONE, GAS, ELECTRICITY, INTERNET, OTHER"
+ " FROM EMPLOYEE E INNER JOIN BILLS B ON E.EMP_ID = B.EMP_ID"
+ " WHERE B.EMP_ID = ? "
+ " OR E.FNAME = ? "
+ " OR E.LNAME = ? "
+ " OR DATE BETWEEN ? AND ? "
+ " ORDER BY B.DATE";
DBConnection con = new DBConnection();
Connection connect = con.getConnection();
PreparedStatement ps = null;
ArrayList<BillsRecord> records = new ArrayList<>();
try {
ps = connect.prepareStatement(sql);
ps.setInt(1, EmpCode);
ps.setString(2, Fname);
ps.setString(3, Lname);
ps.setString(4, sDate);
ps.setString(5, eDate);
ResultSet rs = ps.executeQuery();
if (rs.next()) {
BillsRecord billrec = new BillsRecord();
billrec.setDATE(rs.getString("DT"));
billrec.setEMP_ID(rs.getInt("EMP_ID"));
billrec.setFNAME(rs.getString("FNAME"));
billrec.setLNAME(rs.getString("LNAME"));
billrec.setMONEY_SENT(rs.getDouble("MONEY_SENT"));
billrec.setRENT(rs.getDouble("RENT"));
billrec.setPHONE(rs.getDouble("PHONE"));
billrec.setGAS(rs.getDouble("GAS"));
billrec.setELECTRICITY(rs.getDouble("ELECTRICITY"));
billrec.setINTERNET(rs.getDouble("INTERNET"));
billrec.setOTHER(rs.getDouble("OTHER"));
records.add(billrec);
return records;
}
} catch (SQLException e) {
System.out.println(e.toString());
} finally {
if (ps != null) {
ps.close();
}
if (connect != null) {
connect.close();
}
}
return null;
}
private void search() {
try {
JTextField stxt = ((JTextField) startdatetxt.getDateEditor().getUiComponent());
String sDATE = stxt.getText().trim();
JTextField etxt = ((JTextField) enddatetxt.getDateEditor().getUiComponent());
String eDATE = etxt.getText().trim();
int EMP_ID = Integer.parseInt(this.empidtxt.getText().trim());
String FNAME = this.firstnametxt.getText().trim();
String LNAME = this.lastnametxt.getText().trim();
BillRecordDao billrecdao = new BillRecordDao();
ArrayList<BillsRecord> records = billrecdao.getBillRecordByID(EMP_ID, FNAME, LNAME, sDATE, eDATE);
Object[] tableColumnName = new Object[11];
tableColumnName[0] = "Date";
tableColumnName[1] = "H.License";
tableColumnName[2] = "First Name";
tableColumnName[3] = "Last Name";
tableColumnName[4] = "MONEY SENT";
tableColumnName[5] = "RENT";
tableColumnName[6] = "PHONE";
tableColumnName[7] = "GASE";
tableColumnName[8] = "ELECTRICITY";
tableColumnName[9] = "INTERNET";
tableColumnName[10] = "OTHER";
DefaultTableModel tbd = new DefaultTableModel();
tbd.setColumnIdentifiers(tableColumnName);
this.BillsSummaryTable.setModel(tbd);
Object[] RowRec = new Object[11];
for (int i = 0; i < records.size(); i++) {
RowRec[0] = records.get(i).getDATE();
RowRec[1] = records.get(i).getEMP_ID();
RowRec[2] = records.get(i).getFNAME().toUpperCase();
RowRec[3] = records.get(i).getLNAME().toUpperCase();
RowRec[4] = records.get(i).getMONEY_SENT();
RowRec[5] = records.get(i).getRENT();
RowRec[6] = records.get(i).getPHONE();
RowRec[7] = records.get(i).getGAS();
RowRec[8] = records.get(i).getELECTRICITY();
RowRec[9] = records.get(i).getINTERNET();
RowRec[10] = records.get(i).getOTHER();
tbd.addRow(RowRec);
}
} catch (SQLException e) {
System.out.println(e.toString());
}
}

Basically, you need to create a variable/dynamic query based on the available values
Now, you can do this using something like StringBuilder or even storing each query element in a List or array, but you always end up with the "trailing OR" problem (you need to know when you've got to the last element and not append the "OR" to the String or remove the trailing "OR" from the resulting String). While not difficult, it's just a pain.
However, if you're using Java 8, you can use StringJoiner!
StringJoiner sj = new StringJoiner(" OR ");
String sql = "SELECT B.DATE AS DT, B.EMP_ID, E.FNAME, E.LNAME, MONEY_SENT, RENT, PHONE, GAS, ELECTRICITY, INTERNET, OTHER"
+ " FROM EMPLOYEE E INNER JOIN BILLS B ON E.EMP_ID = B.EMP_ID"
+ " WHERE ";
List values = new ArrayList();
// EmpCode MUST be a Integer, so it can be null
if (EmpCode != null) {
sj.add("B.EMP_ID = ?");
values.add(EmpCode);
}
if (FName != null) {
sj.add("E.FNAME = ?");
values.add(FName);
}
if (LName != null) {
sj.add("E.LNAME = ?");
values.add(LName);
}
if (sDate != null && eDate != null) {
sj.add("DATE BETWEEN ? AND ?");
values.add(sDate);
values.add(eDate);
}
sql += sj.toString();
Connection connect = null;
try (PreparedStatement ps = connect.prepareStatement(sql)) {
for (int index = 0; index < values.size(); index++) {
ps.setObject(index + 1, values.get(index));
}
try (ResultSet rs = ps.executeQuery()) {
if (rs.next()) {
//...
}
}
} catch (SQLException exp) {
exp.printStackTrace();
}
You might also like to have a look at The try-with-resources Statement and have a read through Code Conventions for the Java TM Programming Language, it will make it easier for people to read your code and for you to read others

Fail to convert to internal representation JDBC

Ok so this is my code
public static ArrayList getMaterialerFraOrdreNr(String s_date, String e_date) throws SQLException, InterruptedException {
int tal = 0;
ArrayList nameOfColumns = getNameOfColumns(); // name of columns
ArrayList orderNumber = getOrdre_Nr_FromDB(s_date, e_date); // order number
//første loop kører gennem number of columns
//anden loop kører gennem name of column
ResultSet rs = null;
Connection con = null;
try {
Class.forName(DB.driver);
con = DriverManager.getConnection(DB.URL, DB.ID, DB.PW);
for (int i = 1; i < orderNumber.size(); i++) {
for (int j = 1; j < nameOfColumns.size(); j++) {
String nameOfColum = (String) nameOfColumns.get(i);
int orderNr = (Integer) orderNumber.get(j);
System.out.println("orderNr " + orderNr);
//SELECT v1001 FROM ORDRE_spec WHERE ordre_nr = 1;
String query = "SELECT ? AS ans FROM ordre_spec WHERE ordre_nr = ?";
PreparedStatement prest = con.prepareStatement(query);
prest.setString(1, nameOfColum);
prest.setInt(2, orderNr);
System.out.println("orderNr " + orderNr);
System.out.println("nameOfColum = " + nameOfColum);
rs = prest.executeQuery();
if(rs.next()){
tal = rs.getInt("ans");
MaterialeNum.add(tal);
System.out.println("materiale num = " + MaterialeNum);
}
}
}
} catch (ClassNotFoundException | SQLException ee) {
System.out.println("fail og der er så her");
System.err.println(ee);
} finally {
con.close();
}
System.out.println(kundeNum.toString());
return kundeNum;
}
public static void main(String[] args) throws SQLException, InterruptedException {
NewClass.getMaterialerFraOrdreNr("1990-10-10", "2020-10-10");
}
And my problem is that I'm getting a java.sql.SQLException: Fail to convert to internal representation
I really cant see what the error should be.. plz help if you can see the error :)

String query = "SELECT ? AS ans FROM ordre_spec WHERE ordre_nr = ?";
You cannot parameterize column names. You can only parameterize column values.
Basically you need to do:
String query = "SELECT " + nameOfColum + " AS ans FROM ordre_spec WHERE ordre_nr = ?";
Keep in mind that this is prone to SQL injection if nameOfColum is controllable by enduser. If this is indeed the case, you may want to perform string matching on e.g. \w+ before continuing.