What are the components of DataStage? 

In a SQL Database, a 'correlated subquery' is a kind of sub query yet connected subquery is dependent on another query for a value that is returned. In case of execution, the sub query is executed first and afterwards the correlated query will be executed.

Fact is key performance indicator to analyze the business.From the additive values, which are used to analyse the business by using report generation. Dimension is used to analyze the fact, are the non-additive ( text format) values, Which are used to drill down reports.Without dimension there is no meaning for fact. Measure is the quantity of data we create to process.

BUS Schema is composed of a master suite of confirmed dimension and standardized definition if facts.

The main differenc between View and Materialized View states that -

1. View means it stores the SQL statement in the database and let you use it as a table. Everytime you access the view, the SQL statement executes.

2. Materialized view means it stores the results of the SQL in table form in the database. SQL statement only executes once and after that everytime you run the query, the stored result set is used. Advantage include quick query results.

Data warehouse

- It is a decision support database system for the purpose of organizational needs. 

-It is non volatile, integrated and time variant collection of data

Operational Data Stage

- It is an integrated collection of information. 

-It can contain 90 days of information at maximum.

-ODS supports dynamic data.

-Daily loading is known as incremental load.

-When data is selected from source, selected records are loaded between timestamp of last load and the current time 

-The parameter that are passed to perform are last loaded date and current date

-The first parameter is the stored last run date is read through job parameters

-The second parameter is the current date

Sequence numbers can be generated in Datastage using certain routines. They are

-KeyMgtGetNextVal

-KeyMgtGetNextValConn