I need update vertex and return it as ODocument.
First, i query it, then update properties, and finally return it as ODocument.
But I only able to retrieve Vertex, not OrientVertex:
Vertex vPlace = graph.getVertices("id",id).iterator().next();
I found example in http://orientdb.com/docs/2.2/Graph-Blueprints.html:
Iterable<OrientVertex> results = g.query().has("name", EQUALS, "fast");
but it does not compile: "EQUALS" not found.
How to query vertex as OrientVertex?
is this useful for you?
String dbName = "testDB";
OrientGraphFactory dbfactory = new OrientGraphFactory("remote:127.0.0.1:2424/"+dbName, "root", "root").setupPool(1, 50);
OrientGraph db = dbfactory.getTx();
try {
String query = "select from V where name = ?";
Iterable<OrientVertex> result = db.command(new OCommandSQL(query)).execute("testName");
while(result.iterator().hasNext()){
OrientVertex d = result.iterator().next();
//do something with d
System.out.println(d.getProperty("name"));
}
} catch (Exception e) {
// TODO: handle exception
System.out.println(e);
}
Related
I try to print a query through the java console but nothing comes out. this is my code someone could help me.
I'm new to OrientDB and I'm just learning.
The query I need is to know the shortest path between two nodes and print this query on the Java console. It does not give me any errors but nothing comes out.
public class Graph {
private static final String DB_PATH = "C:/OrientDataBase/shortest_path";
static OrientGraphNoTx DBGraph;
static OrientGraphFactory factory;
public static void main(String[] args) {
factory = new OrientGraphFactory("plocal:"+DB_PATH);
DBGraph = factory.getNoTx();
HashMap<String, Vertex> nodes = new HashMap<String, Vertex>();
for(int i = 0; i <= 1000; i++)
{
Vertex v = DBGraph.addVertex("class:V");
v.setProperty("vertexID", i+"");
nodes.put(i+"", v);
}
try(BufferedReader br = new BufferedReader(new FileReader("C:/OrientDataBase/sp1.csv"))) {
int i=0;
for(String line; (line = br.readLine()) !=null ; ) {
if(i==0){
i++;
}
else{
String[] vertices = line.split(",");
String vertex1 = vertices[0];
String vertex2 = vertices[1];
String weight= vertices[2];
vertex2 = vertex2.replaceAll(" ", "");
Vertex v1 = nodes.get(vertex1);
Vertex v2 = nodes.get(vertex2);
Edge eLives = DBGraph.addEdge(null, v1, v2, "belongs");
eLives.setProperty("weight", weight);
System.out.println(v1+","+v2+","+weight);
String query = "select expand(shortestPath) from (select shortestPath(#10:0,#10:2,BOTH))";
Iterable<OrientVertex> res = DBGraph.command(new OCommandSQL(query)).execute();
while(res.iterator().hasNext()){
OrientVertex v = res.iterator().next();
System.out.println("rid: "+v.getId().toString()+"\tn:"+v.getProperty("n"));
}
}
}
}
catch (IOException e) {
e.printStackTrace();
}
}
}
I tried your code and you have to put the ticks when you do the query so, it becomes:
String query = "select expand(shortestPath) from (select shortestPath(#10:0,#10:2,'BOTH'))";
I used this csv file.
Hope it helps.
Regards
I'm learning RESTful webservices from javabrains website. Here there is a section named Comments and this is related to a message, But I'm unable to know How Can I link these both.
Below is my SQL Tables for Messages and comments.
Messages
Comments
Here Basically, both look pretty same(The table design), but the values differ. And I'm using the below method to send the data.
public Comment addComment(long messageId, Comment comment) throws Exception {
Properties properties = new Properties();
properties.load(getClass().getClassLoader().getResourceAsStream("/config.properties"));
String userName = properties.getProperty("user");
String password = properties.getProperty("pass");
String url = properties.getProperty("Sqldburl");
int key = 0;
try {
Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver").newInstance();
Connection conn = DriverManager.getConnection(url, userName, password);
String query = "select count(*) from Comments";
PreparedStatement ps = conn.prepareStatement(query);
ResultSet rs = ps.executeQuery();
rs.next();
key = rs.getInt(1);
} catch (Exception e) {
System.out.println(e);
}
try {
Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver").newInstance();
Connection conn = DriverManager.getConnection(url, userName, password);
String query = "insert into Comments(id, message, author) values(?,?,?)";
PreparedStatement ps = conn.prepareStatement(query);
ps.setInt(1, key);
ps.setString(2, comment.getMessage());
ps.setString(3, comment.getAuthor());
ps.executeQuery();
} catch (Exception e) {
System.out.println(e);
}
try {
Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver").newInstance();
Connection conn = DriverManager.getConnection(url, userName, password);
String query = "select * from Comments where messageId=?";
PreparedStatement ps = conn.prepareStatement(query);
ps.setLong(1, messageId);
ResultSet rs = ps.executeQuery();
while (rs.next()) {
comment.setAuthor(rs.getString("Author"));
comment.setId(rs.getInt("Id"));
comment.setMessage(rs.getString("message"));
}
} catch (Exception e) {
System.out.println(e + "b3");
}
return comment;
}
After writing this code, I've realized that Here I'm adding a comment for sure into Comments table, But it is no where linked to the Messages.
I know a way, that is I've create a new column in the Comments table and using join operation, I need to update the same messageId in comments table. But I want to know if there is a better way of getting this done, without using the concept of joins.
In MessageBean, there is a map declared as below.
private Map<Long, Comment> comments = new HashMap<>();
#XmlTransient
public Map<Long, Comment> getComments() {
return comments;
}
public void setComments(Map<Long, Comment> comments) {
this.comments = comments;
}
can I take any advantage of this to avoid join?
I write online game. For game logic, I need select random users(etc) from database. How to achive this with java api? What the most perfomance way to do this?
I can use something like(pseudocode): select from User skip(randomNum(0,usersCount)) limit 1 but how write in documentation - skip has bad performance.
I have tried with this code
int numberRandom= 5;
String string="[";
int cluster= db.getMetadata().getSchema().getClass("User").getClusterIds()[0];
for(int i=0;i<numberRandom;i++){
int random=ThreadLocalRandom.current().nextInt(0, 96000);
if(i==(numberRandom-1))
string += cluster+":"+random + "]";
else
string += cluster+":"+random + ",";
}
Iterable<Vertex> result = g.command(new OCommandSQL("select from "+ string)).execute();
for(Vertex v:result)
System.out.println(v.getId());
Let me know if it can be a good solution for you
I wrote two java classes, both are getting X random users from a specific cluster.
The first one seams faster to me. (about 0.8s vs 1.2s)
testRandom.java
public class testRandom {
public static void main(String[] args) {
// TODO Auto-generated method stub
String nomeDb = "RandomUser";
try {
OServerAdmin serverAdmin = new OServerAdmin("remote:localhost/"+nomeDb).connect("root", "root");
if(serverAdmin.existsDatabase()){ // il db esiste
//connessione a db
OrientGraph g = new OrientGraph("remote:localhost/"+nomeDb);
//------------------------------------------------
long Tbegin,Tend;
float millis;
Tbegin = System.currentTimeMillis();
int numberRandom= 5;
int random;
String cluster = "user";
Iterable<Vertex> vertices = g.command(new OCommandSQL("select from cluster:"+cluster)).execute();
List<Vertex> v_array = new ArrayList<Vertex>();
List<Vertex> res = new ArrayList<Vertex>();
for(Vertex v : vertices){
v_array.add(v);
}
int arraysize = v_array.size();
for(int i=0;i<numberRandom;i++){
random=ThreadLocalRandom.current().nextInt(0, arraysize);
res.add(v_array.get(random));
}
for(Vertex v : res){
System.out.println(v.getId());
}
Tend = System.currentTimeMillis();
millis = (Tend-Tbegin);
System.out.println("--Execution time: "+millis/1000+ "s\n");
//------------------------------------------------
//chiude db
g.shutdown();
}
else{
System.out.println("Il database '"+ nomeDb + "' non esiste");
}
serverAdmin.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
testRandomSkip.java
public class testRandom_skip {
public static void main(String[] args) {
// TODO Auto-generated method stub
String nomeDb = "RandomUser";
try {
OServerAdmin serverAdmin = new OServerAdmin("remote:localhost/"+nomeDb).connect("root", "root");
if(serverAdmin.existsDatabase()){ // il db esiste
//connessione a db
OrientGraph g = new OrientGraph("remote:localhost/"+nomeDb);
//------------------------------------------------
long Tbegin,Tend;
float millis;
Tbegin = System.currentTimeMillis();
int numberRandom= 5;
int random;
String cluster = "user";
List<Vertex> res = new ArrayList<Vertex>();
Iterable<Vertex> q_count_V = g.command(new OCommandSQL("select count(*) from cluster:"+cluster)).execute();
Long count_V = 0l;
for(Vertex v : q_count_V){
count_V=v.getProperty("count");
break;
}
for(int i=0;i<numberRandom;i++){
random=(int)ThreadLocalRandom.current().nextLong(0, count_V);
Iterable<Vertex> vertex = g.command(new OCommandSQL("select from cluster:"+cluster+" skip "+random+" limit 1")).execute();
for(Vertex v : vertex){
res.add(v);
break;
}
}
for(Vertex v : res){
System.out.println(v.getId());
}
Tend = System.currentTimeMillis();
millis = (Tend-Tbegin);
System.out.println("--Execution time: "+millis/1000+ "s\n");
//------------------------------------------------
//chiude db
g.shutdown();
}
else{
System.out.println("Il database '"+ nomeDb + "' non esiste");
}
serverAdmin.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
Hope it helps.
Ivan
We are using java jdk 1.7.0_45, postgresql jdbc connector postgresql-9.3-1100.jdbc41.jar.
Here is a synopsis of our problem, as much as possible of code pasted below.
This code:
ResultSet rs = DbConn.getInstance().doQuery("Select d.deptId from Depts d");
while (rs.next()){
System.out.println(rs.getInt("d.deptId"));
Produces the error:
org.postgresql.util.PSQLException: The column name d.deptId was not found in this ResultSet.
This code:
ResultSet rs = DbConn.getInstance().doQuery("Select d.deptId from Depts d");
while (rs.next()){
System.out.println(rs.getInt("deptId"));
Produces no error.
Is there a way, besides removing the "d." from the first query, to make the first code snippet not throw the error message?
Here is the source code:
public class JoinTest {
#Test
public void test(){
boolean pass = false;
try {
ResultSet rs = DbConn.getInstance().doQuery("Select d.deptId from Depts d");
String label = rs.getMetaData().getColumnLabel(1); // What do you get?
System.out.println("label = " + label);
while (rs.next()){
System.out.println(rs.getInt("d.deptId"));
pass = true;
}
} catch (SQLException e) {
e.printStackTrace();
pass=false;
}
assertTrue(pass);
}
#Test
public void test2(){
boolean pass = false;
try {
ResultSet rs = DbConn.getInstance().doQuery("Select d.deptId from Depts d");
while (rs.next()){
System.out.println(rs.getInt("deptId"));
pass = true;
}
} catch (SQLException e) {
e.printStackTrace();
pass=false;
}
assertTrue(pass);
}
}
public class DbConn {
private static String url = "jdbc:postgresql://server:port/schema";
private static Properties props = new Properties(); {
props.setProperty("user","userid");
props.setProperty("password","passwprd");
}
private Connection conn;
private DbConn(){}
private static DbConn instance;
public static DbConn getInstance() throws SQLException{
if (instance == null){
instance = new DbConn();
instance.conn = DriverManager.getConnection(url, props);
}
return instance;
}
public ResultSet doQuery(String query) throws SQLException{
Logger.log("DbConn.doQuery: " + query);
Statement st = conn.createStatement();
ResultSet rs = st.executeQuery(query);
return rs;
}
}
}
The query:
select d.deptId from Depts d
produces a single-column resultset with the result-alias "deptId". There is no "d.deptId" column. If you want one, you can request that as the column alias instead:
select d.deptId AS "d.deptId" from Depts d
PgJDBC can't do anything about this because it has no idea that the resultset column "deptId" is related to the "d.deptId" in the select-list. Teaching it about that would force it to understand way more about the SQL it processes than would be desirable, and lead to maintenance and performance challenges.
The second one works - why isn't that acceptable?
You can also do this:
System.out.println(rs.getInt(1));
If you change the query you have to change the code, too.
I have a problem. When I try to use the "Select distinct" in HSQLDB, the stream of results returns me all rows instead of me returning only distinct rows.
I've tried the following syntax:
SELECT DISTINCT FROM ratings UserID order by UserID;
SELECT DISTINCT (UserID) FROM ratings order by UserID;
SELECT DISTINCT UserID FROM ratings;
SELECT DISTINCT (UserID) FROM ratings;
None of them works. What is the problem?
If anyone able to help me I appreciate.
Thank you.
The function code where I perform the action is as follows:
private void readUserFile(String filename) {
try {
//Verify if file users exists
boolean exists = (new File(filename)).exists();
if (!exists) {
//If file users not exists create one, bases on distinct users that exist in ratings table
ResultSet rsUsers = jdbcTemplate.getDataSource().getConnection().createStatement().executeQuery("SELECT DISTINCT UserID FROM ratings order by UserID;");
List<String> users = new ArrayList<String>();
while (rsUsers.next()) {
users.add(String.valueOf(rsUsers.getInt(1)));
}
rsUsers.close();
//Create and write to file
BufferedWriter f = null;
f = new BufferedWriter(new FileWriter(filename));
for (String user : users) {
f.write(user);
f.newLine();
}
f.close();
}
PreparedStatement prstInsert = con.prepareStatement("INSERT INTO users VALUES (?)");
BufferedReader in = new BufferedReader(new FileReader(filename));
int i = 0;
while (true) {
String s = in.readLine();
if (s == null) { // end of file
log.info("Total imported users: " + i);
break;
}
i++;
int userid = Integer.parseInt(s);
prstInsert.setInt(1, userid);
if (i != 0 && Math.round((double) i / 100) == ((double) i / 100)) {
log.info("Imported users: " + i);
}
prstInsert.executeUpdate();
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
}
}