Oracle Training in Kolkata

Why Oracle Is So Important

• Oracle is a fascinating product, and a mesmerizing company to watch.
• The company's principal, Larry Ellison, is certainly the most flamboyant person in the industry, far more engaging than anyone in a similar position in either Microsoft or IBM.
• His adventures with the Americas Cup, and the endless procession of starlets and super models who have graced his arm make him the stuff of tabloids and paparazzi.
• Nobody finds Bill Gates or even Steve Jobs this interesting.
• While this is all fun, I regard it as a distraction from the real reason why Oracle is so important.
• There is one critical thing to observe about Oracle, aside from the fact that it works very, very well for the purpose for which it is intended.
• That is its cost. Oracle is expensive. Street price wise, if you are talking Enterprise Edition, Oracle Database 10g is an order of magnitude more expensive than either of its competitors: Microsoft SQL Server or IBM DB2.
• Yet it manages to dominate the enterprise database management space, according to most of the current market share surveys.
• I liken this to BMW outselling Toyota in the global car market. It's counter intuitive. Why would a more expensive product outsell a less expensive product, all other things being equal? When you think about it, a Toyota provides identical functionality to a BMW generally.
• Similar to the car market, SQL Server is a perfectly fine product which works just as well as Oracle in most respects.
• Furthermore, Microsoft has consistently improved the capabilities of SQL Server relative to Oracle. Microsoft SQL Server is definitely less expensive than Oracle Database 10g.
• You could even say that Oracle kicks Microsoft's butt in this space.
• So why would the customer pay the extra money for Oracle? Simple.
• The customer really, really, really cares about the data being managed by Oracle.
• In other words, this data is the most critical data to the customer, and therefore worth the money spent to manage it.
• It's the customer's crown jewels in other words. The company's critical enterprise resource management system is very likely to be managed by Oracle.
• And given that the customer has paid the price to run Oracle, the tendency will be to put more and more data onto Oracle, despite the cost.
• Oracle is simply addictive. It works, and works well.
• Once you have bitten the bullet, you tend to keep biting it.
• Needless to say, customers are very conservative about radically changing the environment in which they store their most critical data.
• Since Oracle has become firmly entrenched in this niche, it is likely that they will continue to dominate in this area for a long time to come.
• This situation creates what I call the "halo effect".
• In enterprises which run Oracle, it is the most visible software product in the data center.
• The Oracle data must be more reliable, more available, more backed up, and more protected than any other data.
• A storage, server or OS vendor who supports the Oracle environment is managing the customer's crown jewels.
• If you can store the Oracle database data, you can damn sure store the customer's Microsoft Exchange, Microsoft SQL Server, or file system data.
• I take the position that this is the reason why Linux has penetrated the enterprise OS market.
• Before Oracle endorsed Linux, Red Hat and the other Linux vendors were struggling to establish a toe hold in the data center.
• They were relegated to web servers and other less critical functions in engineering labs.
• Linux was the stuff of geeks and propeller heads. Nobody took it seriously.
• The whole open source thing was viewed with deep suspicion.
• Once Oracle started pushing Linux as a database server OS, all that changed almost overnight.
• The enterprise market for Linux exploded. Suddenly, Red Hat was the darling of Wall Street, and Linux started showing up inside the data center in Fortune 1000 companies.
• At the same time, the proprietary UNIX market (especially Sun Solaris) took a huge dump. Sun's stock went into the tank, and they have struggled ever since.
• Even though everyone knows that Sun Solaris still owns a huge part of the Oracle database server OS market. By endorsing Linux at the expense of proprietary UNIX, Larry Ellison moved the market.
• That's the halo effect at work.
• This means that the business of storing Oracle data, while an interesting business in its own right, is much more important than the dollar impact of that business.
• This also means that it is critical that EMC continue to aggressively pursue the Oracle market, and maintain its leadership position in this market relative to NetApp.
• My tenure at EMC has largely been about this challenge, and our strategy in facing it.
• In my next post I will explain why EMC technology is the best available solution for storing Oracle database files, and how we intend to continue to improve that technology.

• Oracle is one of the popular databases provided by Oracle Corporation, which works on relational management concepts and hence it is referred to as Oracle RDBMS as well.
• It is widely used for online transaction processing, data warehousing, and enterprise grid computing.

• Both VARCHAR and VARCHAR2 are Oracle data types that are used to store character strings of variable length.
• VARCHAR can store characters up to 2000 bytes while VARCHAR2 can store up to 4000 bytes.
• VARCHAR will hold the space for characters defined during declaration even if all of them are not used whereas VARCHAR2 will release the unused space.

• Both the commands are used to remove data from the database.
• The difference between the two include,
• TRUNCATE is a DDL operation while DELETE is a DML operation.
• TRUNCATE drops the structure of a database and hence cannot be rolled back while the DELETE command can be rolled back.
• The TRUNCATE command will free the object storage space while the DELETE command does not.

• RAW datatype is used to store variable-length binary data or byte strings.
• The difference between RAW VARCHAR2 datatype is that PL/SQL does not recognize this data type and hence, cannot do any conversions when RAW data is transferred to different systems.
• This data type can only be queried or inserted in a table.

• Joins are used to extract data from multiple tables using some common columns or conditions.
• There are various types of Joins as listed below:
• INNER JOIN
• OUTER JOIN
• CROSS JOINS;
• EQUI JOIN
• ANTI JOIN
• SEMI JOIN

• COALESCE function is used to return the first non-null expression from the list of arguments provided in the expression.
• There must be a minimum of two arguments in an expression.