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Q: Could two schemas have some data items in common?
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Why are data schemas important?

Data schemas are important because they define the structure and organization of the data, ensuring consistency, accuracy, and integrity. They help in understanding the relationships between different data elements and provide a blueprint for how data is stored and accessed within a database or system. Properly designed data schemas also promote data quality, facilitate data integration, and support efficient querying and analysis.


Explain the difference of internal external and conceptual schemas how are these schema layers related to the concept of logical and physical data independence?

External schemas allows data access to be customized (and authorized) at the level of individual users or groups of users. Conceptual (logical) schemas describes all the data that is actually stored in the database. While there are several views for a given database, there is exactly one conceptual schema to all users. Internal (physical) schemas summarize how the relations described in the conceptual schema are actually stored on disk (or other physical media). External schemas provide logical data independence, while conceptual schemas offer physical data independence.


What schemas do you use in Multidimensional Modelling?

In Multidimensional Modelling, common schemas used are Star Schema and Snowflake Schema. Star Schema involves a central fact table connected to multiple dimension tables, while Snowflake Schema normalizes the dimension tables by further breaking them down into sub-dimension tables. These schemas help organize data hierarchically for efficient querying and analysis in multidimensional databases.


How are the internal external and conceptual schemas related to concept of logical and physical data independence?

The internal schema represents the physical storage structure of data, the external schema represents how different users view the data, and the conceptual schema defines the logical structure of the entire database. Logical data independence means that the conceptual schema can change without affecting the external schemas, while physical data independence means that changes in the physical storage structures do not affect the conceptual or external schemas.


What Logical data independence and physical data?

Logical data independence refers to the ability to modify the conceptual schema without changing the external schemas or application programs. In contrast, physical data independence allows changes to the internal schema – like indexes and storage structures – without affecting the conceptual or external schemas.


Description of database subschema?

What are the purpose of developing a sub-schema in database? In database management, the Subschema pronounced "sub-skee-mah." is an individual user's partial view of the database while the schema is the entire database. It is the applications programmer's view of the data within the database pertinent to the specific application. A subschema has access to those areas, set types, record types, data items, and data aggregates of interest in the pertinent application to which it was designed. Naturally, a software system usually has more than one programmer assigned and includes more than one application. This means there are usually many different sub schemas for each schema. The following are a few of the many reasons sub schemas are used: # Sub schemas provide different views of the data to the user and the programmer, who do not need to know all the data contained in the entire database. # Sub schemas enhance security factors and prohibit data compromise. # Sub schemas aid the DBA while assuring data integrity. Each data item included in the subschema will be assigned a location in the user working area (UWA). The UWA is conceptually a loading and unloading zone, where all data provided by the DBMS in response to a CALL for data is delivered. It is also where all data to be picked up by the DBMS must be placed.


The collection of data The sum of the data items divided by the number of data items?

The Mean


What is meant by Actuate Encyclopedia Volume and what is its significance?

The volume is where your reports are stored. You need to understand that a volume can also contain many "folders" which are tied to separate database schemas. Think of an encyclopedia volume as a reports database, and the folders as database schemas, and you begin to understand how Actuate is organizing your reports, metadata, and Actuate system data. -C The volume is where your reports are stored. You need to understand that a volume can also contain many "folders" which are tied to separate database schemas. Think of an encyclopedia volume as a reports database, and the folders as database schemas, and you begin to understand how Actuate is organizing your reports, metadata, and Actuate system data. -C


How data is represented in dbms?

Data is represented/organized in a dbms in the form of Schemas, tables, rows and columns One DBMS may have multiple Schemas One Schema may have multiple tables One table may have multiple rows One row may have multiple columns If these tables are related to one another it forms a RDBMS - A Relational DBMS


What is a collection of unprocessed items such as text numbers and images?

A collection of unprocessed items is known as data.


What is the meaning of normalized data in data warehouse?

Data warehouses are designed for quick access to large amounts of historical data. Read operations dominate over write operations. Under these conditions, normalization takes a back seat to performance optimization. A different design methodology, called dimensional design is used when planning a data warehouse. There are two common categories of schemas used in data warehousing: star schemas and snow flake schemas. A star schema has a central fact table, surrounded by dimension tables. The fact table contains columns called measures, which are aggregated in queries. The fact table is related to the dimension tables. The dimension tables may have levels, which are implemented as columns. For example, a dimension table named Location may contain columns for Continent, Country, StateProvince and City. This dimension table is not normalized. If you normalize the dimension tables, then each level is placed in its own table. Normalizing the dimension tables results in a snow flake schema.


Is median always sometimes or never in a data set?

If the sample has an odd number of items in it then the median will definitely be in the sample at least once because the median is value of the set of data items whose value(s) are in the middle of the sample when the sample is sorted from smallest to largest. If the sample has an even number of items in it then if the middle items are different the median will be their average, and it will differ from all of the items in the data set. I could continue in this vein but already you can see that the median sometimes occurs in a data set but not always.