Lets say the two databases in question are local and remote, so the sql to create the materialized view to load immediately and refresh everyday is

CREATE MATERIALIZED VIEW MV_CUSTOMERBALANCE 
BUILD IMMEDIATE
REFRESH FORCE START WITH ROUND(SYSDATE) + 23/24
NEXT SYSDATE + 1
AS
SELECT customer.name , account.balance, accounttype.name 
FROM customer , account@remotedb account, accounttype@remotedb accounttype
WHERE
customer.id = account.customerid
AND account.accounttyppeid = accounttype.id
/

SELECT customer.name , account.balance, accounttype.name 
FROM customer , account@remotedb account, accounttype@remotedb accounttype
WHERE
customer.id = account.customerid
AND account.accounttyppeid = accounttype.id
/

CREATE MATERIALIZED VIEW MV_CUSTOMERBALANCE 
BUILD IMMEDIATE
REFRESH FORCE START WITH ROUND(SYSDATE) + 23/24
NEXT SYSDATE + 1
AS
SELECT customer.name , account.balance, accounttype.name 
FROM customer , account@remoteaccount account, accounttype@remoteaccounttype accounttype
WHERE
customer.id = account.customerid
AND account.accounttyppeid = accounttype.id
/

I go regularly to this store to get Horizon organic milk for my family, about 60% of the time I see milk I need NOT in stock, okay I can live with that, may be lots of folks are buying organic milk, but not when it happens frequently, especially when the store knows how much milk was ordered (or supplied from the warehouse) and how much milk was sold, the store should be able to figure out that organic milk gets sold out pretty fast, putting my Business Intelligence (BI) hat on, I think the store should be able to predict when they are going to run out of organic milk ( for that matter any product), its especially frustrating when they have all the data they need to get it done.

One more non usage of data that really makes me red is, when the organic milk in the store is already expired (past the sell by date). I mean how hard is it for someone to generate a list of all the products that expire today and ask the store associates to remove them from the shelves by the end of the day, especially when its edible items.

For example.
Lets assume there are two tables Parent(ParentID) and Child(ChildID)

SESSION_A >create table parent (parentId number(10));
Table created.
SESSION_A >create table child (childId number(10));
Table created.
SESSION_A >insert into parent values (100);
1 row created.
SESSION_A >insert into child values (200);
1 row created.
SESSION_A >commit;
Commit complete.
SESSION_A >select * from parent;
  PARENTID
----------
       100

SESSION_A >select * from child;

   CHILDID

----------

       200

SESSION_A >

Now lets create a situation where a deadlock happens. There are two sessions connected to the same database and same user, SESSION_A and SESSION_B are the two sessions in question.

SESSION_A >update parent set parentid = 1000 where parentid=100;
1 row updated.
SESSION_B >update child set childid = 2000 where childid = 200;
1 row updated.
SESSION_B >update parent set parentid = 2001 where parentid=100;
--Waiting For Lock on Row in Parent Table, held by SESSION_A
SESSION_A >update child set childid = 1001 where childid = 200;
update child set childid = 1001 where childid = 200
       *
ERROR at line 1:
ORA-00060: deadlock detected while waiting for resource
--SESSION_A requesting lock on row, held by SESSION_B causing deadlock.
SESSION_A >

After you get the ORA-00060 error the statement update child set childid = 1001 where childid = 200; is rolled back.. but SESSION_B is still waiting for the lock on the Parent table to be released.

So when your application get the ORA-00060 or any deadlock exception in any other database, explicitly rollback your transaction (not just the current statement) so that all the changes made in the transaction and all the locks held by the transaction are released.

This is especially nice since the Oracle for Mac was the most voted requirement on mix.oracle.com

If you upgrade to Oracle 11g (I know lot of you are waiting for 11gR2), you will find that passwords are case sensitive. Here is an example of case sensitive passwords.

c:\Software>sqlplus bddd/bddd@dosa
SQL*Plus: Release 11.1.0.6.0 - Production on Wed May 6 15:17:43 2009
Copyright (c) 1982, 2007, Oracle.  All rights reserved.
Connected to:
Oracle Database 11g Enterprise Edition Release 11.1.0.6.0 - Production
With the Partitioning and OLAP options
BDDD@dosa >

Lets try to connect with a upper case password

c:\Software>sqlplus bddd/BDDD@dosa
SQL*Plus: Release 11.1.0.6.0 - Production on Wed May 6 15:19:25 2009
Copyright (c) 1982, 2007, Oracle.  All rights reserved.
ERROR:
ORA-01017: invalid username/password; logon denied
Enter user-name:

So what does this mean to apps running with 10g, that get ported to run with 11g. Make sure that the password set in the properties files is of the correct case.

You can also revert to 10g behavior by changing sec_case_sensitive_logon parameter to FALSE, since its TRUE by default.

alter system set sec_case_sensitive_logon=FALSE;

COLUMN OBJECT_NAME FORMAT A30
COLUMN STATUS FORMAT A15
spool objects.log

CREATE TABLE FOO (ID NUMBER(10), NAME VARCHAR2(30));

CREATE OR REPLACE TRIGGER TRIG_FOO
BEFORE INSERT OR UPDATE
ON FOO
REFERENCING OLD AS OLD NEW AS NEW
FOR EACH ROW
BEGIN
	IF :NEW.name IS NULL THEN
		:NEW.name := 'NOT AVAILABLE';
	END IF;
END;
/

CREATE OR REPLACE FUNCTION FUNCTION_GET_NAME_FOR_FOOID(inFooId number)
RETURN VARCHAR2
IS
fooName VARCHAR2(30);
BEGIN
	BEGIN
     SELECT name INTO fooName FROM foo WHERE id = inFooId ;
     EXCEPTION
         WHEN NO_DATA_FOUND THEN 
     		RETURN 'NOT FOUND';
 	END;
     RETURN fooName;
 END;
/

SELECT OBJECT_NAME,STATUS FROM USER_OBJECTS WHERE STATUS='INVALID';

ALTER TABLE FOO ADD ( DESCRIPTION VARCHAR2(100));

SELECT OBJECT_NAME,STATUS FROM USER_OBJECTS WHERE STATUS='INVALID';

spool off

ALTER TRIGGER TRIG_FOO COMPILE;
ALTER FUNCTION FUNCTION_GET_NAME_FOR_FOOID COMPILE;

SELECT OBJECT_NAME,STATUS FROM USER_OBJECTS WHERE STATUS='INVALID';

CREATE TABLE FOO (PREFERRED_TIME DATE NULL);
INSERT INTO FOO (TO_DATE('11:34','HH24:MI'));

SELECT TO_CHAR(PREFERRED_TIME, 'dd-mon-yyyy hh24:mi:ss') from FOO;
-----------------------
01-feb-2009 11:24:00

on the client side you will have to know to ignore the date component, this is possible area for confusion in future, since I could have many preferences over different months and my preferred time would have different date components, ideally I would just want the time, otherwise I would think having a time component and the date being a constant known value like 01/01/0001. We could achieve this using a BEFORE INSERT/UPDATE trigger which keeps the time component but updates the date component to a known constant value or you can also use your OR mapping layer like hibernate to set the value as such. If you are using hibernate, you can map the filed using the java.sql.Time object and the date is automatically set to 01/01/1970. SqlServer 2008 seems has a Time data type.

1. Make the stored procedure handle one object/table only and not multiple objects or tables.
2. Do not commit open transactions inside the stored procedures.
3. Do not do business logic in stored procedures.
4. If they are straight CRUD stored procedures, see if you can you generate the stored procedure code using some metadata?
5. Make sure creation and execution of the stored procedures is part of your Continuous Integration build and developer build.
6. Make sure stored procedures (or the metadata used to generate them) is under Version Control, have seen many problems when the stored procedure version does not match application code version
7. Develop against the production stack database.
8. Make sure exceptions thrown by the database are passed back to the application.

Just finished writing a article about Behavior Driven Design applied to Databases or Behavior Driven Database Design. for Methods and Tools.

@Column(name = "qReferenceId")
public Long getQReferenceId() {
return qReferenceId;
}

Where qReferenceId is data provided to our application via a external reference, we do not have a QReference Object or Table for FK references.When trying to query this object using DetachedQuery, this Simple expression was used.

public List findByQReferenceId(Long id) {
     final SimpleExpression matchesId = Property.forName("qReferenceId").eq(id);
    DetachedCriteria criteria = DetachedCriteria.forClass(Movie.class);
    criteria = criteria.add(matchesId);
    List movies = (List) getHibernateTemplate().findByCriteria(criteria);
    return movies;
}

When running this method, I kept getting errors shown below.

could not resolve property: qReferenceId of: com.example.Movie; 

nested exception is org.hibernate.QueryException: could not resolve property: qReferenceId of: com.example.Movie

....

....

I thought I had a spelling mistake on the property name and also tried many other combinations. Finally I said why not use "QReferenceId" and suddenly everything was hunky dory, this kind of weirdness does not happen when working with property names that do not have consecutive double uppercase characters in the getter/setter for the property. very interesting. So this method worked

public List findByQReferenceId(Long id) {
    final SimpleExpression matchesId = Property.forName("QReferenceId").eq(id);
    DetachedCriteria criteria = DetachedCriteria.forClass(Movie.class);
    criteria = criteria.add(matchesId);
    List movies = (List) getHibernateTemplate().findByCriteria(criteria);
    return movies;
}