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 Lance Andersen's BlogFebruary 2006 ArchivesJDBC 4.0 Wrapper InterfacePosted by lancea on February 23, 2006 at 02:46 PM | Permalink | Comments (1)The Wrapper interface provides a mechanism for JDBC users to be able to access an instance of a resource which has been wrapped for architectural reasons. This mechanism helps to eliminate the need to use non-standard means to access vendor specific resources. The following JDBC interfaces are subinterfaces of the Wrapper interface:
The Wrapper interface consists of two methods:
Statement stmt = conn.createStatement();
Class clzz = Class.forName("oracle.jdbc.OracleStatement");
OracleStatement os;
if(stmt.isWrapperFor(clzz)) {
os = stmt.unwrap(clzz);
os.defineColumnType(1, Types.NUMBER);
}
JDBC 4.0 SQLException EnhancementsPosted by lancea on February 21, 2006 at 11:58 AM | Permalink | Comments (0)The following enhancements were made in JDBC 4.0 in order to provide a better developer's experience when dealing with SQLExceptions:
Causal Relationship SupportWe have added support for the Java SE chained exception mechanism by adding additional constructors allowing for the cause to be specified. The cause could be a non-SQLException, it is just what resulted in the SQLException being thrown.This feature does not reduce the need for the getSQLException() method as it is possible for multiple unique SQLExceptions to be generated (not all DBs do this currently but could going forward and is allowed by the SQL Standard) due to executing a statement on the backend. Your code would look something like the following to process the causal relationships:
catch(SQLException ex) {
while(ex != null) {
System.out.println("SQLState:" + ex.getSQLState());
System.out.println("Error Code:" + ex.getErrorCode());
System.out.println("Message:" + ex.getMessage());
Throwable t = ex.getCause();
while(t != null) {
System.out.println("Cause:" + t);
t = t.getCause();
}
ex = ex.getNextException();
}
}
For Each Loop SupportThe SQLException class now implements the Iterable interface providing support for the For each loop feature added in J2SE 5.0. The navigation of the loop will walk through the SQLException and its cause (if any):
catch(SQLException ex) {
for(Throwable e : ex ) {
System.out.println("Error encountered: " + e);
}
}
Categorization of SQLExceptionsJDBC 4.0 has introduced two categories of SQLException: SQLTransientException and SQLNonTransientException.A SQLNonTransientException would be thrown in instances where a retry of the same operation would fail unless the cause of the SQLException is corrected. The following Exceptions have been added, each extending SQLNonTransientException:
A SQLTransientException will be thrown in situations where a previously failed operation might be able to succeed when the operation is retried without any intervention by application-level functionality. The following Exceptions have been added, each extending SQLTransientException:
Please refer to the JDBC specification to see the SQLState Class value code that is associated with the new SQLExceptions.
Correct SQLState for a DataTruncation on a write operationWe have also fixed a long outstanding JDBC bug so that the SQLState of 22001 is now returned for a DataTruncation Exception during a write operation to a data source.JDBC 4.0 keeps moving forwardPosted by lancea on February 17, 2006 at 09:23 AM | Permalink | Comments (19)JDBC 4.0 has just completed public draft review and the EG is working on closing the last few issues. One of the interfaces that I expect to change signficantly is the SQLXML interface. Here is a list of the major features being added to JDBC 4:
Some of the features have been enhanced in the current drops of Mustang (part of the specification evolution). We have also spent a lot of time trying to clarify and improve the javadoc method and interface descriptions as well as various sections of the JDBC paper spec that have resulted in some confusion in the past for developers. We will continue to review and address as many issues that we can prior to the official release of Mustang. As we wind down the spec work, we will also be focusing on addressing as many outstanding JDBC bugs as possible. Getting Started using Derby with Glassfish and SJSAS 8.2Posted by lancea on February 07, 2006 at 11:10 AM | Permalink | Comments (0)Glassfish and SJSAS 8.2 introduce two new asadmin commands for starting and stopping the Derby Network Server. The start-database command may be used to start an instance of the Derby network server:
start-database [––dbhost 0.0.0.0] [––dbport 1527] [––dbhome install_dir/derby]The default value for the host is 0.0.0.0, which allows for Derby to listen on localhost as well as the ip/hostname interfaces. The value for the dbhome property represents the location of where the derby databases reside. The default is <glassfish/sjsas_HOME>/derby. You may also use the asadmin command stop-database to shutdown an instance of the Derby network server that is running:
stop-database [––dbhost 0.0.0.0] [––dbport 1527] The derby configuration that ships with glassfish and SJSAS 8.2 also provides several useful scripts which can assist you with utilizing Derby successfully. To run these scripts, you need to do the following:
The following scripts are available for use in the <glassfish/sjsas_HOME>/derby/frameworks/NetworkServer/bin directory:
For more information, see the Derby tools and admin guide for additional details on these utilities
Exporting Tables from Pointbase to DerbyPosted by lancea on February 06, 2006 at 04:06 PM | Permalink | Comments (0)Brian Leonard has a nice article which shows you how to capture the ddl for a table in pointbase and create the same table in Derby using Netbeans 5.0. Another option for doing this is by using the commander tool and the 'unload database' command:
./startcommander.sh
Do you wish to create a new Database. (Yes (Y) or No (N))? [default: N]:
Enter product to connect with: (Embedded (E) or Server (S))? [default: E]: e
Enter driver to use? [default: [com.pointbase.jdbc.jdbcUniversalDriver]:
Enter database URL? [default: [jdbc:pointbase:embedded:sample]:
Enter Username? [default: PBPUBLIC]:
Enter Password? [default: PBPUBLIC]:
PointBase Commander 5.2 ECF build 294 size restricted version EMBEDDED
Interactive SQL command language. SunOS/5.9
(C) Copyright 2004 DataMirror Mobile Solutions, Inc. All rights reserved.
Licensed to: Sun_customer_demo_use
For commercial version contact PointBase at:
pointbase.com
PHONE: 1-877-238-8798 (US & CANADA)
1-408-961-1100 (International)
WEBSITE: www.pointbase.com
SQL>unload database sampledb.sql;
SQL> unload database sampledb.sql;
SQL> 13 Row(s) Unloaded. (PBPUBLIC.CUSTOMER_TBL)
SQL> 4 Row(s) Unloaded. (PBPUBLIC.DISCOUNT_CODE_TBL)
SQL> 30 Row(s) Unloaded. (PBPUBLIC.MANUFACTURE_TBL)
SQL> 11 Row(s) Unloaded. (PBPUBLIC.MICRO_MARKETS_TBL)
SQL> 9 Row(s) Unloaded. (PBPUBLIC.OFFICE_TBL)
SQL> 4 Row(s) Unloaded. (PBPUBLIC.OFFICE_TYPE_CODE_TBL)
SQL> 15 Row(s) Unloaded. (PBPUBLIC.ORDER_TBL)
SQL> 6 Row(s) Unloaded. (PBPUBLIC.PRODUCT_CODE_TBL)
SQL> 30 Row(s) Unloaded. (PBPUBLIC.PRODUCT_TBL)
SQL> 10 Row(s) Unloaded. (PBPUBLIC.SALES_REP_DATA_TBL)
SQL> 10 Row(s) Unloaded. (PBPUBLIC.SALES_REP_TBL)
SQL> 52 Row(s) Unloaded. (PBPUBLIC.SALES_TAX_CODE_TBL)
SQL> 12 Table(s) Unloaded.
SQL> quit;
The results from executing the 'unload database' command is written in the above example to the file sampledb.sql.
The sampledb.sql file contains all of the DDL requried to create the necessary tables and indexes.
It also contains the DML to insert the data back into the database. The commander command RUN is intended to be used import the data into another pointbase database using the script that was generated.
Here is an example of what the INSERT statments and associated data look like in the generated file:
INSERT INTO "ADVENTURE"."CATEGORY" (
"CATID", "LOCALE", "NAME", "DESCRIPTION", "IMAGEURI" )
VALUES( ?, ?, ?, ?, ? );
{
'ISLAND ','en_US','Island Adventures','Experience an island paradise in a way fit for your needs.','Island_Adventures.gif'
'JUNGLE ','en_US','Jungle Adventures','Experience a jungle paradise in a way fit for your needs.','Jungle_Adventures.gif'
'MOUNTAIN ','en_US','Mountain Adventures','Experience an elevated paradise with a view.','Mountain_Adventures.gif'
'ORBITAL ','en_US','Orbital Adventures','Experience a vacuum paradise with a beautiful view and where no one can hear you scream.','Space_Adventures.gif'
'WESTERN ','en_US','Western Adventures','Enjoy the Wild West.','Western_Adventures.gif'
'SOUTH_POLE ','en_US','South Pole Adventures','Experience a frozen paradise in a way fit for your needs.','SouthPole_Adventures.gif'
};
You could easily edit the file generated from the commander 'unload database' command so that it only consisted of the DDL (it would not be hard to write a program which would process the insert statements and perhaps I will try and find time to do so).
As a simple test, I used the unload database command against the pointbase sample database. I edited the script that was generated making the following changes:
I then repeated the same experiment for the sun-appserv-samples database requiring the following additional changes to the generated sql file:
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