Returning values from Nested Tables using JDBC

Posted by Steve Racanovic | Posted in | Posted on 1:25 PM

0

When running a select statement in sqlplus on a nested tables we get the results returned. However the same can not be said when running the same statement through JDBC. He is an example of returning values from a nested table with JDBC.

1. Here's how the sql script looks like to create the type and tables.


drop table person;
drop type nested_addresses;
drop type address;

create or replace type address as object(
street varchar2(50),
city varchar2(20),
postcode varchar2(8),
state varchar(8))
/

create or replace type nested_addresses as table of address
/

create table person (
firstname varchar(20),
lastname varchar(20),
address_list nested_addresses
) nested table address_list store as person_addresses
/

insert into person values ('Fred','Flinstone', nested_addresses(address('345 Cave Stone Road', 'Bedrock', 'BR345','BR'),address('1313 Cobblestone Way', 'Bedville', 'BV1313','BV')))
/

commit
/

2. If I now run the select statement we can see the results:

scott@orcl> set head on feedback on
scott@orcl> set pages 999
scott@orcl> set linesize 120
scott@orcl> col firsname format a20
scott@orcl> col lastname format a20
scott@orcl> col address_list format a50
scott@orcl> select firstname, lastname, address_list from person;

FIRSTNAME LASTNAME ADDRESS_LIST(STREET, CITY, POSTCODE, STATE)
-------------------- -------------------- --------------------------------------------------
Fred Flinstone NESTED_ADDRESSES(ADDRESS('345 Cave Stone Road', 'B
edrock', 'BR345', 'BR'), ADDRESS('1313 Cobblestone
Way', 'Bedville', 'BV1313', 'BV'))


1 row selected.


3. However if I now run the same select query, through a java client using JDBC we will get null values returned.

import java.sql.*;

public class Person {
public static void main(String[] args) throws SQLException, ClassNotFoundException {

// connection parameters
String dbUrl = "jdbc:oracle:thin:@sracanov-au2.au.oracle.com:1522:orcl";
String dbUser = "scott";
String dbPass = "tiger";

// load the driver
Class.forName("oracle.jdbc.driver.OracleDriver");

// create connection
Connection con = DriverManager.getConnection(dbUrl, dbUser, dbPass);

// query the table
Statement s = con.createStatement();
String query = "select firstname, lastname, address_list from person";
ResultSet res = s.executeQuery(query);

// look at the result set
res.next();
System.out.println("First Name: " + res.getString(1));
System.out.println("Last Name: " + res.getString(2));
System.out.println("Address: " + res.getString(3));

// close connection
con.close();
}
}

[sracanov@sracanov-au C]$ java -version
java version "1.6.0_16"
Java(TM) SE Runtime Environment (build 1.6.0_16-b01)
Java HotSpot(TM) Client VM (build 14.2-b01, mixed mode, sharing)

[sracanov@sracanov-au C]$ javac -cp .;"D:\My Contents\My Software\Oracle\JDBC\Drivers\11.2.0.1.0\ojdbc6.jar" Person.java

[sracanov@sracanov-au C]$ java -cp .;"D:\My Contents\My Software\Oracle\JDBC\Drivers\11.2.0.1.0\ojdbc6.jar" Person
First Name: Fred
Last Name: Flinstone
Address: null


This is because we need to get a collection of objects and handle them in java by returning arrays elements. The correct way to return this is:


import java.sql.*;

public class Person1 {
public static void main(String[] args) throws SQLException,
ClassNotFoundException {

// connection parameters
String dbUrl = "jdbc:oracle:thin:@sracanov-au2.au.oracle.com:1522:orcl";
String dbUser = "scott";
String dbPass = "tiger";

// load the driver
Class.forName("oracle.jdbc.driver.OracleDriver");

// create connection
Connection con = DriverManager.getConnection(dbUrl, dbUser, dbPass);

// query the table
Statement s = con.createStatement();
String query = "select firstname, lastname, address_list from person";
ResultSet res = s.executeQuery(query);

// look at the result set
while (res.next()) {
int addresscounter=1;
System.out.println("First Name: " + res.getString(1));
System.out.println("Last Name: " + res.getString(2));
Array array = res.getArray(3);
Object[] address_list = (Object[]) array.getArray();
for (int i = 0; i < address_list.length; i++) {
Struct address = (Struct) address_list[i];
Object[] attrib = address.getAttributes();
for (int j = 0; j < attrib.length; j++) {
System.out.println("Address " + addresscounter + ": " + attrib[j]);
}
addresscounter++;
}
}

// close connection
con.close();
}
}

[sracanov@sracanov-au C]$ javac -cp .;"D:\My Contents\My Software\Oracle\JDBC\Drivers\11.2.0.1.0\ojdbc6.jar" Person1.java

[sracanov@sracanov-au C]$ java -cp .;"D:\My Contents\My Software\Oracle\JDBC\Drivers\11.2.0.1.0\ojdbc6.jar" Person1
First Name: Fred
Last Name: Flinstone
Address 1: 345 Cave Stone Road
Address 1: Bedrock
Address 1: BR345
Address 1: BR
Address 2: 1313 Cobblestone Way
Address 2: Bedville
Address 2: BV1313
Address 2: BV


http://download.oracle.com/docs/cd/E11882_01/java.112/e10589/oraarr.htm#i1059642

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