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Return array of deleted elements postgresql JDBC

This is my database:
dragons
id, key, name, age, creation_date
users
id, name, user, pass
users_dragons
user_id, dragon_id
So this is my code for deleting dragons from the database that have a bigger key that the passed and belongs to a determination user. The SQL query works perfectly for deleting them but not for returning the array of keys from the deleted elements.
I tried using PreparedStatement but later I checked, as far as I know, that this class doesn't return arrays, and the CallableStatement is only for executing processes in the db, and I don't know how they return arrays.
String query = "" +
"DELETE FROM dragons " +
"WHERE id IN (SELECT d.id FROM dragons d, users u, users_dragons ud" +
" WHERE d.key > ?" +
" AND ud.dragon_id = d.iD" +
" AND ud.user_id in (select id from users where id = ?)) RETURNING key INTO ?";
CallableStatement callableStatement = connection.prepareCall(query);
int pointer = 0;
callableStatement.setInt(++pointer, key);
callableStatement.setInt(++pointer, credentials.id);
callableStatement.registerOutParameter(++pointer, Types.INTEGER);
callableStatement.executeUpdate();
return (int []) callableStatement.getArray(1).getArray();
The code is giving me the error, but is obvious because the CallableStatement needs a postgres function to run and not a simple SQL query
org.postgresql.util.PSQLException: This statement does not declare an OUT parameter.
Use { ?= call ... } to declare one.
at org.postgresql.jdbc.PgCallableStatement.registerOutParameter
.......
It would be really helpful how would be the correct JDBC algorithm to delete the elements from the database and return the array of keys of the deleted items.

You treat such a statement like a normal SELECT statement: use java.sql.PreparedStatement.executeQuery() or java.sql.Statement.executeQuery(String sql) to execute the statement and get a result set.
java.sql.CallableStatement is for calling Procedures (but you don't need it in PostgreSQL).

Java & SQL - Can't create duplicate values in my primary and foreign key

Go easy on me, middle school teacher taking a CS class. I've got a Java program that asks for user name, height, weight, does some calculations and gives results to the user. I now need to store this data in a database. I can get the data to store until I start using primary and foreign keys.
Here is the error I can't figure out:
Error: java.sql.SQLIntegrityConstraintViolationException: The statement was aborted because it would have caused a duplicate key value in a unique or primary key constraint or unique index identified by 'SQL180429151131780' defined on 'USERPROFILE'.
Here is my table:
drop table stayfitapp.userdata;
drop table stayfitapp.userprofile;
drop schema stayfitapp restrict;
create schema stayfitapp;
create table stayfitapp.userprofile
(
profileName varchar(255) not null primary key,
profileGender varchar(255) not null
);
create table stayfitapp.userdata
(
profileAge double not null,
profileWeight double not null,
profileHeight double not null,
profileWaistCircumference double not null,
profileHipCircumference double not null,
profileName varchar(255),
foreign key (profileName) references stayfitapp.userprofile(profileName)
);
Here is the section of the "app" that writes to the table...
public void save(){
try {
String query = "insert into stayfitapp.userprofile" + "(profileName, profileGender)" + "values" + "(?,?)";
String query2 = "insert into stayfitapp.userdata" + "(profileAge, profileWeight, profileHeight, profileWaistCircumference, profileHipCircumference)" + "values" + "(?,?,?,?,?)";
Connection myConnection = DriverManager.getConnection("jdbc:derby://localhost:1527/stayfitDB2", "username", "password");
Statement myStatement = myConnection.createStatement();
//Statement myStatement2 = myConnection.createStatement();
PreparedStatement prepared = myConnection.prepareStatement(query);
prepared.setString(1, profileName);
prepared.setString(2, profileGender);
PreparedStatement prepared2 = myConnection.prepareStatement(query2);
prepared2.setDouble(1, profileAge);
prepared2.setDouble(2, profileWeight);
prepared2.setDouble(3, profileHeight);
prepared2.setDouble(4, profileWaistCircumference);
prepared2.setDouble(5, profileHipCircumference);
int rowsAffected = prepared.executeUpdate();
int rowsAffected2 = prepared2.executeUpdate();
if(rowsAffected==0)
{
System.out.println("Warning: User data did not save!");
}
else
{
System.out.println("User info saved!");
}
}
catch(SQLException e)
{
System.out.println("Error: "+e.toString());
}

Your save() method will attempt to add the user to the stayfitapp.userprofile table. This table has a field called profileName. profileName is the "primary key" so no duplicate values are allowed.
The error that you are getting is saying that you cannot add(insert) the record to the table because the table already has a record with the same name.
Does your program work okay if you use a different name each time?
You will need to add some logic to your program to deal with the scenario where the profileName already exists in the table. This will probably involve deleting or updating the existing record.

This is the problem.
insert into stayfitapp.userprofile"
+ "(profileName, profileGender)" + "values" , etc
You have nothing to check to see if a record already exists. Something like this would work better.
insert into stayfitapp.userprofile
profileName, profileGender
select distinct ?, ?
from someSmallTable
where not exists (
select 1
from stayfitapp.userprofile
where profileName = ?
)
The someSmallTable bit depends on your database engine, which you didn't specify.

I ended up writing a method to check if the username was already in the profile table. If the username was a duplicate I only wrote to the data table. If the username was new I wrote to both tables.
Thank you for your help! I'm sure there was a more efficient method (figuratively and literally) but I'm on to my final project and nearly surviving an actual CS class.

Inserting Into Cassandra using batch statements

I am inserting data into Cassandra coming from a csv file using batch statements. My table looks like this
create table exposures(expoid bigint,fileid bigint,studyid text, projname text, w text, x text, y text, z text)
System.out.println(colDataMap);
String keyspace = "orchtablespaces";
String tabName = fileName;
//String tableFile = "/home/blr-lt-202/empAccount.txt";
String tableFile = fname;
Set<String> colNamesSet = colDataMap.keySet();
String[] colNames = colNamesSet.toArray(new String[colNamesSet.size()]);
System.out.println("ColNames ::" +colNames);
String makeStatement = makeSt(keyspace,tabName,colNames);
System.out.println("makeStatement ::"+makeStatement);
if(count==65534)
{
session.executeAsync(bs);
count = 0;
bs = new BatchStatement();
}
PreparedStatement statement = session.prepare(makeStatement);
//bcz expo id and seq_n
String expoid =(String) colDataMap.get("expoid");
String Seq_No = (String) colDataMap.get("Seq_No");
colDataMap.put(expoid, Long.valueOf(expoid));
colDataMap.put("Seq_No", Long.valueOf(Seq_No));
BoundStatement query = statement.bind(colDataMap.values().toArray(new Object[colDataMap.size()]));
//BoundStatement query = statement.bind(colDataMap.get("Seq_No"),colDataMap.get("fileId"),colDataMap.get("studyId"),colDataMap.get("projectName"),colDataMap.get("dosetxt"),colDataMap.get("sdurtunit"),colDataMap.get("durtunit"));
System.out.println("query "+query);
bs.add(query);
count++;
}
session.executeAsync(bs);
session.close();
The Map ColDataMap has all the Cassandra Table col Names as key and their values In the map as shown below
{Seq_No=0, fileId=123, studyId=786, w=PreCLinic, x=Tasq 30mg/kg, y=12 days, z=12 days}
Set<String> colNamesSet =colDataMap.keySet();
String[] colNames = colNamesSet.toArray(new String[colNamesSet.size()]);
System.out.println("ColNames ::" +colNames);
String makeStatement = makeSt(keyspace,tabName,colNames);
System.out.println("makeStatement ::"+makeStatement);
The method makeSt prepares the prepared Statement
makeStatement ::INSERT INTO orchtablespaces.EXPOSURES ( Seq_No,fileId,studyId,w,x,y,z ) values ( ?,?,?,?,?,?,? )
This is all fine. Then I do the following
PreparedStatement statement = session.prepare(makeStatement);
//bcz expoid and seq_no are of type bigint int the cassandra table
String expoid =(String) colDataMap.get("expoid");
String Seq_No = (String) colDataMap.get("Seq_No");
colDataMap.put(expoid, Long.valueOf(expoid));
colDataMap.put("Seq_No", Long.valueOf(Seq_No));
BoundStatement query = statement.bind(colDataMap.values().toArray(new Object[colDataMap.size()]));
When i run the program I am getting the following error
com.datastax.driver.core.exceptions.NoHostAvailableException.copy(NoHostAvailableException.java:84)
com.datastax.driver.core.DefaultResultSetFuture.extractCauseFromExecutionException(DefaultResultSetFuture.java:289)com.test.load.microarr.CopyOfLoadMicroArr.transformSourceFile(CopyOfLoadMicroArr.java:486)com.test.load.microarr.CopyOfLoadMicroArr.loadData(CopyOfLoadMicroArr.java:149)
com.test.load.microarr.CopyOfLoadMicroArr.main(CopyOfLoadMicroArr.java:114)
Caused by: com.datastax.driver.core.exceptions.NoHostAvailableException: All host(s) tried for query failed (no host was tried)
com.datastax.driver.core.RequestHandler.sendRequest(RequestHandler.java:107)
com.datastax.driver.core.SessionManager.execute(SessionManager.java:538)
com.datastax.driver.core.SessionManager.prepareAsync(SessionManager.java:124)
com.datastax.driver.core.AbstractSession.prepare(AbstractSession.java:77)
... 3 more
com.datastax.driver.core.AbstractSession.prepare(AbstractSession.java:79)
The exact line where the program is breaking is line 486 and that is at
PreparedStatement statement = session.prepare(makeStatement);
I am using DataStax Cassandra 2.1.8 .. any suggestions and solutions would be really helpful !! Thanks !

You definitely have problem with the connection to the cassandra.
Form the Datastax Java driver documentation:
NoHostAvailableException - if no host in the cluster can be contacted successfully to prepare this statement.
And form the error description
Exception thrown when a query cannot be performed because no host are
available. This exception is thrown if
either there is no host live in
the cluster at the moment of the query
all host that have been tried
have failed due to a connection problem
For debugging purpose, the
list of hosts that have been tried along with the failure cause can be
retrieved using the errors method.
Try to catch this error and output list of tried host - this could help you detect is there are wrong host or wrong port. Use getErrors() method - http://docs.datastax.com/en/drivers/java/2.0/com/datastax/driver/core/exceptions/NoHostAvailableException.html#getErrors()

Passing a mysql query to the database using a java program

I am new to mysql and I am trying to connect to the database using a Java Program and I am passing a mysql query.
public class dbconnect {
public static void main(String[] args) throws SQLException,ClassNotFoundException {
Class.forName("com.mysql.jdbc.Driver");
Connection conn =DriverManager.getConnection("jdbc:mysql://localhost:3306/mydatabase?user=root&password=root");
Statement st = conn.createStatement();
int custid= 0;
String myname = null;
String query = "select name from groups where customer_id = 2;";
//This query has a problem can anyone help me fix it.
System.out.println(query);
ResultSet rs1 = st.executeQuery(query);
System.out.println("after query");
while (rs1.next()){
custid = rs1.getInt("customer_id");
myname = rs1.getString("name");
System.out.println(myname);
System.out.println(custid);
}
}
}
I am passing a query "select name from groups where customer_id = 2" .
Here "name" is a coloumn,"groups" is a table and "customer_id" is another column. In the program when I give this query(no typos) I get the following error
Exception in thread "main" java.sql.SQLException: Column 'customer_id' not found.
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1073)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:987)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:982)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:927)
at com.mysql.jdbc.ResultSetImpl.findColumn(ResultSetImpl.java:1144)
at com.mysql.jdbc.ResultSetImpl.getInt(ResultSetImpl.java:2815)
at com.memoir.client.widgets.memogen.dbconnect.main(dbconnect.java:61)
I have checked with the table , customer_id is present in the table . They are no spelling mistakes also .Even then it says that customer_id column is not found .
Can anyone help me fix it.

The query needs to be:
String query = "select name, customer_id from groups where customer_id = 2;";

Honestly it doesn't make any sense, your query is
String query = "select name from groups where customer_id = 2;";
and you expect to get customer_id ??
as you are already passing customer_id in where clause you don't need to get it back again from db.
String query = "select customer_id,name from groups where customer_id = 2;";
The above would work with your current code .

You are accessing only name column in query and you are try to get "customer_id" in while loop from result set
while (rs1.next()){
custid = rs1.getInt("customer_id"); // **error is here - remove this line or change your query**
myname = rs1.getString("name");
System.out.println(myname);
System.out.println(custid);
}

Your problem is that you are trying to get an invalid column ("cutomer_id") from the result set which contains only the "name" column.
To resolve this you have to select also the "customer_id" in your query:
"select name, customer_id from groups where customer_id = 2";

custid = rs1.getInt("customer_id");
you result set does not have customer_id
Include that too in your query

try this
String mysqlquery = "select name, customer_id from groups where customer_id=2";

How to insert a row into a that table has an increment id with CachedRowSet?

I'm trying to insert a row into a table that has an increment id with CachedRowSet(I'm using Java wit Java DB), but I got the following SQLException:
java.sql.SQLException: Failed on insert row
at...
SQLState: null
Error Code: 0
Message: Failed on insert row
Here's my code snippet:
private static String urlString = "jdbc:derby:testdb;create=true";
private static String userName = "testUser";
private static String password = "testPassword";
...
CachedRowSet crs = new CachedRowSetImpl();
crs.setUrl(urlString);
crs.setUsername(userName);
crs.setPassword(password);
crs.setCommand("SELECT * FROM test_table");
crs.execute();
crs.moveToInsertRow();
crs.updateString("str_value", "testValue");
crs.insertRow();
crs.moveToCurrentRow();
crs.acceptChanges();
The SQLException is thrown from crs.inertRow().
The CachedRowSet works well if the table does not have an auto increment id.
How can I successfully do this?
other details:
I use the following code to create my table:
conn = DriverManager.getConnection(urlString, userName, password);
Statement stmt = conn.createStatement();
stmt.execute("CREATE TABLE test_table("
+ "id INTEGER NOT NULL GENERATED ALWAYS AS IDENTITY (START WITH 1, INCREMENT BY 1),"
+ "str_value VARCHAR(20) NOT NULL,"
+ "CONSTRAINT primary_key PRIMARY KEY (id))");
System.out.println("Talbe test_table created.");

This is a duplicate of Failed on insert row using CachedRowSet.
Unfortunately, that happens because of the API definition:
Throws:
SQLException - if a database access error occurs; the result set concurrency is CONCUR_READ_ONLY, this method is called on a closed result set, if this method is called when the cursor is not on the insert row, or if not all of non-nullable columns in the insert row have been given a non-null value
You may be better off using JdbcRowSetImpl.
You can only stick with the CachedRowSet if you remove the NOT NULL constraint of the id column. Unfortunately, this would also mean to remove the PK constraint. I'd assume that is too big a sacrifice, but it's either that or no CachedRowSet.

try this
crs.updateNull(1);
crs.insertRow();
where 1 is your PK. Worcked for me in MySQL