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What is wrong with my query?? It has no error at all

I have a problem with my sql query in Java. As you can see below, the query is supposed to return rph_id but it returns only 0, so it only proceeds to the else method.
At first, I did not use prepareStatement but many suggest that I use prepareStatement. But it still won't work. After checking both suggestions, I think my problem is on the query but I don't know what.
public class RphDAO{
static int rph_id;
public static RPHS getRph(RPHS rph) {
try {
currentCon = ConnectionManager.getConnection();
ps=currentCon.prepareStatement("select * from rphs where rph_id=?");
ps.setInt(1, rph_id);
ResultSet rs = ps.executeQuery();
if (rs.next()) {
rs.getInt("rph_id");
rph.setRph_id(rph_id);
rph.setValid(true);
} else {
rph.setValid(false);
}
}
...
return rph;
}
}
It should return an existing id, not 0.

Here:
if (rs.next()) {
rs.getInt("rph_id");
rph.setRph_id(rph_id);
rph.setValid(true);
You get a value from the ResultSet rs ... to then throw that result away.
Probably you meant something like:
rph_id = rs.getInt("rph_id");
On the other hand, your request those entries that have rph_id==1, so I don't see what other value than 1 you expect to find here. Most likely, you want to look into other parts of that result set, and somehow pull those into variables/fields of some object.
It seems as if the OP is simply not familiar with using ResultSet, thus I think the real answer is: go and read a good tutorial on this subject. You can't learn how to use a new API by trial and error. Read its documentation, or a good tutorial that shows you how to use it properly!

I think you should use COUNT instead in your sql since it is no point in setting the id if it is already correct and also use the id from the object given as parameter to the method for consistency.
public static RPHS getRph(RPHS rph) {
try {
currentCon = ConnectionManager.getConnection();
ps=currentCon.prepareStatement("select COUNT(*) from rphs where rph_id=?");
ps.setInt(1, rph.getRph_id);
ResultSet rs = ps.executeQuery();
int count = 0;
if (rs.next()) {
count = rs.getInt(1);
}
rph.setValid(count == 1);
}

SQL returning wrong data

for some reason my SQL connection seems to be returning a completely invalid response. Somehow between one call and the next (after a brief period of time, about a second) it returns an entirely different value. I should note that I have other rows set up the exact same way that do not have this problem.
I should note that I'm using apache dbcp2 for the SQL datasource which is where the getConnection() is calling. I should note that everything else works just fine but not this for some reason.
Hope I included enough information. I'm not asking for you to do the work for me, I just have no idea what the issue could be here.
//First call
//Note Global.TOKEN_TTL is a constant value of 300000
System.out.println((System.currentTimeMillis() + Global.TOKEN_TTL));
Start.getSQLConnection().setTTL(userID, (System.currentTimeMillis() + Global.TOKEN_TTL));
System.out.println(Start.getSQLConnection().getTTL(userID));
//Second Call
System.out.println(System.currentTimeMillis());
System.out.println(Start.getSQLConnection().getTTL(userID));
Output
----Call one
System call: 1529456964416
DB call: 1529456964416
DB Actual: 1529456964416
----Call two
System call: 1529456665144
DB call: 4294967295
DB Actual: 1529456964416
The database is set up using MariaDB. The row is a signed BIGINT with a length of 20.
Retrieval
Code below is in order of called first to last:
First call:
getLong("adbname", "TTL", "SELECT TTL FROM atablename WHERE ID=?;", userID);
Second call:
public long getLong(String database, String tag, String sql, Object... parameters) throws SQLException {
return (long) getObject(database, sql, tag, parameters);
}
Third call:
public Object getObject(String database, String sql, String tag, Object... parameters) throws SQLException {
Connection conn = getConnection(database);
conn.setAutoCommit(false);
PreparedStatement stmt = conn.prepareStatement(sql);
assert parameters != null && parameters.length > 0;
for (int i = 0; i < parameters.length; i++) {
stmt.setObject(i + 1, parameters[i]);
}
ResultSet rs = stmt.executeQuery();
if (!rs.next())
return null;
Object o = rs.getObject(tag);
conn.commit();
if (rs != null)
rs.close();
if (stmt != null)
stmt.close();
if (conn != null)
conn.close();
return o;
}
Setting
public boolean setTTL(long userID, long TTL) throws SQLException {
return executeUpdate("adbname", "UPDATE atablename SET TTL=? WHERE ID=?;", TTL, userID);
}
//The actual work
public boolean executeUpdate(String database, String sql, Object... parameters) throws SQLException {
Connection conn = getConnection(database);
conn.setAutoCommit(false);
PreparedStatement stmt = conn.prepareStatement(sql);
for (int i = 0; i < parameters.length; i++) {
stmt.setObject(i + 1, parameters[i]);
}
boolean result = stmt.executeUpdate() > 0;
conn.commit();
if (stmt != null)
stmt.close();
if (conn != null)
conn.close();
return result;
}

I hate to admit this but #Scary Wombat was right. It ended up (not exactly) being one of those "oh I forgot to tell you" scenarios.
The issue was a design flaw in the way that the user ID was being retrieved due to the fact that they weren't guaranteed to be unique (pretty serious flaw on my part). It was pulling data from another user.
Thanks a ton for all the help, while it didn't directly solve the problem you gave me insight into a few things that I was doing wrong with SQL and storage in general. I'll make sure to remember this one, thanks again!

The clue: 4294967295 = 2^32-1
Smells like you have a 32-bit build of some product, possibly even the OS.
Or you are using INT UNSIGNED when you need BIGINT. You say "The row is a signed BIGINT with a length of 20" -- Please provide SHOW CREATE TABLE.
And what is to keep Object o = rs.getObject(tag); from being limited to 32 bits?

ResultSet.getInt() ERROR [closed]

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Edit the question to include desired behavior, a specific problem or error, and the shortest code necessary to reproduce the problem. This will help others answer the question.
Closed 8 years ago.
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so I'm trying to connect to a database using java.. there's a problem at a function I wrote getOutSymptoms.
Here's the code
package database_console;
import java.sql.*;
public class DBConnect {
private Connection con;
private Statement st;
private ResultSet rs;
public DBConnect(){
try {
Class.forName("com.mysql.jdbc.Driver");
try {
con = DriverManager.getConnection("jdbc:mysql://localhost:3306/users", "root", "admin");
st = con.createStatement();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public int getOutSymptoms(int userID) throws SQLException{
String query = "SELECT `user`.`out_symptoms` FROM user WHERE (`user`.`id` =" + userID + ")";
rs = st.executeQuery(query);
int out_symptoms_value = rs.getInt("out_symptoms");
st.close();
return out_symptoms_value;
}
the error is at the getOutSymptoms function, at the line:
int out_symptoms_value = rs.getInt("out_symptoms");
why is that? and how can I fix it?
thank u so much.

You need to iterate through your result set in order to get the returned rows. When you first get your new ResultSet, it's not pointing to any particular row (its pointer is set to a row before first) and you need to call rs.next() method at least once to get to the actual results.
If you know there can be only one result you can do something like this:
if (rs.next()) {
int out_symptoms_value = rs.getInt("out_symptoms");
//do other stuff
} else {
//query returned no results
}
If you expect to have more than one row returned, then you can do this:
while(rs.next()) {
int out_symptoms_value = rs.getInt("out_symptoms");
//do the rest of processing
}
TLDR: You need to call rs.next() at least once to get to the actual results.

In order to start using a ResultSet, you must call the next() method. Although you haven't stated the exact error, you will definitely run into this problem unless it is added before you call getInt().
http://docs.oracle.com/javase/tutorial/jdbc/basics/retrieving.html

you need to iterate through the resultSet object using rs.next() to get the value. resultSet doesn't point to the actual row but when you call rs.next() it points to first result.
while(rs.next(){
int d = rs.getInt(" ");
}
rs.next() returns a boolean value , incase nothing is returned the loop will not execute & you will not get an Exception at runtime.

You have already passed the database name in connection string so change this
String query = "SELECT `user`.`out_symptoms` FROM user WHERE (`user`.`id` =" + userID + ")";
to
String query = "SELECT out_symptoms FROM tableName WHERE id =" + userID;
Then just iterate over the obtained ResultSet like this
while(rs.next()) {
int out_symptoms_value = rs.getInt("out_symptoms");
}
Moreover its good to use PreparedStatement instead of Statement which cna prevent you from sql injection

ResultSet search Error in JDBC

so I am a beginer in JDBC - SQL Programming. I need a little advice which is most probably about SYNTAX.
So, Problem = I'm trying to search a record which has name(string provided in function argument) in the record. Following is my code. Now I've designed this code in such a way that there can be more than 1 records with the same name, so all of that records' data will be printed (by ShowData() Function).
protected static void SearchbyName (String toCompareName)
{
Statement stmt = null;
ResultSet rs = null;
Connection conn = null;
boolean flag = false; //to confirm if record has found atleast once
try
{
Class.forName("com.mysql.jdbc.Driver").newInstance();
conn = DriverManager.getConnection(url, username, password);
stmt = conn.createStatement();
rs = stmt.executeQuery("SELECT idEmployee FROM employee WHERE name = ' "+toCompareName+" ' ");
if( !(rs.next()) ) //if ResultSet is not empty
{
while(rs.next()) //reading all records with the same name, extracted by Query
{
int foundID = rs.getInt("idEmployee"); //extracting ID of found record
ShowRecord(foundID); //prints record of foundID fromDB
flag = true; //set flag
}
}
if(flag==false) //if no record found
{
JOptionPane.showMessageDialog(null, "ERROR:: No Records Found..", "Not Found", JOptionPane.ERROR_MESSAGE);
}
//close connection
if(rs!=null)
{ rs.close(); }
if(stmt!=null)
{ stmt.close(); }
if(conn!=null)
{ conn.close(); }
}
catch(SQLException e)
{ System.err.println(e); }
catch(Exception e)
{ System.err.println(e); }
}
So here it is. As far as my understanding goes, there is some problem with either RESULTSET rs or the Query I'm executing.
Kindly help. & if you can suggest a better approach for search, sure do please. I'm going to write 4 more functions SearchbyAge, SearchbyQualification, SearchbySpecialization on the same pattern.

Just this is enough
while(rs.next()) //reading all records with the same name, extracted by Query
{
int foundID = rs.getInt("idEmployee"); //extracting ID of found record
ShowRecord(foundID); //prints record of foundID fromDB
flag = true; //set flag
}
You don't have to check the data in resultset this way with a if case
if( !(rs.next()) )
This will move to the next record in the resultset

SOVLED
My error was in query. I was putting spaces in string's syntax which I was comparing.
WRONG = `"(.. WHERE name = " ' +toCompareName+ '" ");
RIGHT = `"(.. WHERE name = "'+toCompareName+'" ");
So thats it. Hope it helps to anyone else. :)

Getting an Integer From MySQL Select Statement

I would like to get an integer saved in my MySql DB into an Integer in Java. I have a Table, that includes PlayerName and Level. I would like to get The Level (Integer) From a Specific Player. And then Add Integer "Value" to it. Then put it back in the DB. My Code up to now is:
public void addinputPData(String loc, int value, Player player, String playername){
//add input Player Data
try{
logm("Putting Kill Death Int Data into " +player.getName() + "'s Profile!");
Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/WebCom", "root", "MyPW");
int ovalue = -1;
Statement stmt = (Statement) con.createStatement();
ResultSet rs = stmt.executeQuery("SELECT "+loc+" FROM PlayerData WHERE PlayerName='"+playername+"'");
if(rs.next()){
ovalue= rs.getInt(loc);
}
if(ovalue == -1){
logm("Error Occured");
}
int nvalue = value + ovalue;
String insert = "UPDATE PlayerData SET "+ loc + "='" + nvalue + "' WHERE PlayerName='" + playername + "'";
stmt.executeUpdate(insert);
con.close();
}catch(Exception e){
logm("Could Not Send Data To MYSQL DATABASE SERVER s: "+ e.getMessage());
}
}
I don't know why this won't work, Is there anything obvious that i am missing? Thank you in advance.

So first what you must understand is that when you won't use parametrized statements, there is big danger of SQL Injection. So your code is very dirty written.
So anyway, use PreparedStatement with parametrized SQL statements for much more better performace. Now rewrite your code like this:
final String SELECT_QUERY = "SELECT level FROM PlayerData WHERE PlayerName = ?";
final String UPDATE_QUERY = "UPDATE PlayerData SET level = ? WHERE PlayerName = ?";
public boolean dataMethod(String playerName) {
Connection con = null;
PreparedStatement ps = null;
PreparedStatement ps1 = null;
ResultSet rs = null;
int dataLevel = 0;
try {
// getConnection etc...
ps = con.prepareStatement(SELECT_QUERY);
ps.setString(1, playerName) // first param is order of ? param, starts with 1(not 0)
rs = ps.executeQuery();
while (rs.next()) {
dataLevel = rs.getInt();
}
if (dataLevel > 0) {
ps1 = con.prepareStatement(UPDATE_QUERY);
ps1.setInt(1, dataLevel);
ps1.setString(2, playerName);
ps1.executeUpdate();
}
return true;
}
catch (SQLExcetion ex) {
Logger.getLogger(YourClass.class.getName()).log(Level.SEVERE, null, ex);
return false;
}
finally {
if (con != null) {
con.close();
}
}
}
Step by step, first init your statement, sets parameters if you have then when you use select, you will retrieve data in ResultSet that is table of data generated with query. imlicitly cursor in ResultSet is position before first row so you have to use next() method to go on current row and with the help of getter method you add data from ResultSet to your variable. Then you check if it's correct, if do, init second statement and execute it. And that's all.
But you should consider when you use more that 1 operation, sets autoCommit on false and all operations will do in one Transaction, because implicitly in JDBC is one operation = one transaction. And second, you should consider to use SQL stored procedures for add any data, update data or delete. It's more safer yet and less code. So let database working when it able to do it and also it's faster of course.
At the last, really you should think about this approach and makes your code more safer, faster and cleaner. Not have look on simplicity but on efficiency, compability and security.
More about SQL Injection
And when you decided right to use stored procedure, you can use it like this:
CREATE OR REPLACE PROCEDURE SOME_NAME(VARCHAR v_name PlayerData.name%type)
AS
BEGIN
SET TRANSACTION ISOLATION LEVEL SERIALIZABLE;
// body
COMMIT;
EXCEPTION
WHEN OTHERS THEN
ROLLBACK;
END;
So now you have to create String for call procedure.
final String CALL_SOMENAME = "{call SOME_NAME(?)}";
Then intead of PreparedStatement you have to use CallableStatement that is interface used to execute SQL stored procedures.
cs.prepareCall(CALL_SOMENAME); // Creates a cs object for calling db stored procedures
cs.setString(1, playerName);
cs.execute();
I don't know why many people searching the easiest way to do something and don't look at performance and readability of code.
Regards

In the UPDATE statement, you're inserting the value for the "loc" column as a string (there are single quotes around the value). If the database column is an integer, then this could be causing a problem.
Tip: JDBC provides a class called PreparedStatement. This class allow you to build SQL queries safely. It makes sure that all user input is properly escaped in order to avoid security vulnerabilities.
PreparedStatement ps = con.prepareStatement("UPDATE PlayerData SET " + loc + " = ? WHERE PlayerName = ?");
ps.setInt(1, nvalue);
ps.setString(2, playername);
ps.execute();