Informatica Reference

Archive for February 2012

Stored Procedure transformation is an Passive & Connected or UnConnected transformation. It is useful to automate time-consuming tasks and it is also used in error handling, to drop and recreate indexes and to determine the space in database, a specialized calculation.

Data Modeling is representing the real world set of data structures or entities and their relationship in their of data models, required for a database. Data Modelling consists of various types like :

  • Conceptual data modeling
  • Logical data modeling
  • Physical data modeling
  • Dimensional data modeling

DECODE is used to decode a CHAR or VARCHAR2 or NUMBER into any of several different character strings or numbers based on value. That is DECODE does a value-by-value substitution.

An Implicit cursor is one created “automatically” for you by Oracle when you execute a query. It is simpler to code
An Explicit cursor is one you create yourself. It takes more code, but gives more control – for example, you can just open-fetch-close if you only want the first record and don’t care if there are others DBA_DATA_FILES.

INSTR function search string for sub-string and returns an integer indicating the position of the character in string that is the first character of this occurrence.

SUBSTR function return a portion of string, beginning at character position, substring_length characters long.SUBSTR calculates lengths using characters as defined by the input character set.

  • TABLES
  • VIEWS
  • INDEXES
  • SYNONYMS
  • SEQUENCES
  • TABLESPACES

Triggers are fired implicitly on the tables/views on which they are created. There are various advantages of using a trigger. Some of them are:

  • Suppose we need to validate a DML statement(insert/Update/Delete) that modifies a table then we can write a trigger on the table that gets fired implicitly whenever DML statement is executed on that table.
  • Another reason of using triggers can be for automatic updation of one or more tables whenever a DML/DDL statement is executed for the table on which the trigger is created.
  • Triggers can be used to enforce constraints. For eg : Any insert/update/ Delete statements should not be allowed on a particular table after office hours. For enforcing this constraint Triggers should be used.
  • Triggers can be used to publish information about database events to subscribers. Database event can be a system event like Database startup or shutdown or it can be a user even like User loggin in or user logoff.