Schema Objects



Welcome  friends , Today we are starting with the Objects of Micro strategy. The objects are the building blocks of the applications .

Facts
Facts are an object which relates the numeric data values from the data warehouse to the Micro Strategy.
A fact has two characteristics: it is numerical and aggregatable. Examples of facts include revenue, inventory, and account balances. There are some cases where a fact is not numerical or aggregatable, but these are rare. Facts are stored in the data warehouse in fact tables. These fact tables comprise different columns, each cell representing a specific piece of information. Metrics, which are business measures, are created from this information. SQL aggregations, such as SUM and AVG, are performed on the facts in the database tables. For example, in the following SQL statement, the ORDER_AMT column in the warehouse might correspond to the Order Amount fact in the Micro Strategy environment:

SELECT sum (a21.ORDER_AMT) REGION
FROM ORDER_FACTa21
JOIN LU_EMPLOYEEa22
ON (a21.EMP_ID = a22.EMP_ID)
WHERE a22.CALL_CTR_ID in (5, 9, 12)

In this example, ORDER_AMT is the fact, whereas sum (a21.ORDER_AMT) represents a metric.
 A fact entry level is the lowest set of attribute at which fact is stored.

Attributes
Once you have determined all the facts necessary to complete your business model, you identify the attributes for that model. Attributes act as holders of information, allowing you to add context to your facts in a report. For example, if you had $10,000 in revenue, that number does not mean anything in a business sense unless you know the context, such as which region, the designated time frame for the sales, and what was the labor involved. Simply put, attributes provide categories for the summarization of data.
Attributes represent entities in the business model and normally identified by unique ID column in the data warehouse. It acts like a column header and the data that appears are the elements.

Attribute elements
Attribute elements are the data shown on the report. Think of them as a sub-level of the attribute. For example, City might be the attribute, whereas Boston, Baltlmore, and New York are the attribute elements.
In the data warehouse, attributes are usually represented by columns in a table, and attribute elements are represented by the rows as shown in the figure.


In the SQL Statement, the attributes are in the Select and Group by sections.
Select Store_ID, Year, sum (Sale) From Store_tbl
Group by Store_ID, Year:
Types of Attribute:
·         Simple Attribute
·         Implicit Attribute
·         Derived  Attribute
·         Compound Attribute
Simple Attribute
Simple Attribute is made up of one or more expressions, with a simple attribute definition, we can define an attribute as a column, constant or simple expression. It directly mapped to the database column.
Implicit Attribute
   Implicit Attribute is a virtual or constant attribute that doesn’t physically exist in the database because it is created at the application level. It has its own expression.
Derived Attribute
Derived Attribute has its value is determined by an expression which combines two or more columns in the database to create a new column.
Compound attribute     
Compound attribute is an attribute with multiple columns specified as the ID column. This implies that more than one ID column is needed to uniquely identify the elements of that attribute. All of the ID forms of the compound attribute should be grouped together.
 Attribute Form
As part of creating attributes in MSTR project, you create forms for each attributes. It enables you to display different type of descriptive information about an attribute .It is an identifiers or descriptors of an attribute. Every attribute must have at least one form and at most have two.
                  ID:  Attributes must contain at least one ID form, which uniquely identifies the attribute. These are typically numeric because processing a numbers is more rapid than text.
                  Description Form: Contain textual descriptions of the attribute elements.
Types of Attribute form expressions:
·         Simple Expressions
·         Implicit Expressions
·         Derived Expressions
  Simple Expressions
A simple expression is based on a single warehouse column. The definition of the simple expression includes the tables in which the column is found.
Implicit Expressions
An implicit expression create implicit attribute, and has a constant value.
Derived Expressions
Expressions which contain more than just a column in a table are known as derived expressions. Any operation on a column, such as adding a constant, adding another column, or setting the expression to be an absolute value, create a derived expression.

Comments