Give an example of the following concepts. Data Definition Language (DDL) statem

Question

Give an example of the following concepts. Data Definition Language (DDL) statement Data Manipulation Language (DML) statement Schema Data model Instances Domain constraints Business Rule constrains Data dictionary Transaction View Casual end user Parametric End user Sophisticated end user Primary Key Attribute Foreign Key Attribute Unique Key Attribute Value Sets (Domains) of Attributes Aggregate function Geographic Information System (GIS) Online Analytical Processing (OLAP) Give an example of the following concepts. Data Definition Language (DDL) statement Data Manipulation Language (DML) statement Schema Data model Instances Domain constraints Business Rule constrains Data dictionary Transaction View Casual end user Parametric End user Sophisticated end user Primary Key Attribute Foreign Key Attribute Unique Key Attribute Value Sets (Domains) of Attributes Aggregate function Geographic Information System (GIS) Online Analytical Processing (OLAP) Give an example of the following concepts. Data Definition Language (DDL) statement Data Manipulation Language (DML) statement Schema Data model Instances Domain constraints Business Rule constrains Data dictionary Transaction View Casual end user Parametric End user Sophisticated end user Primary Key Attribute Foreign Key Attribute Unique Key Attribute Value Sets (Domains) of Attributes Aggregate function Geographic Information System (GIS) Online Analytical Processing (OLAP)

Explanation / Answer

DDL - statements are used to define the database structure or schema. Some examples:

DML - statements are used for managing data within schema objects. Some examples:

Data Model
Data model is the first step in designing the database. Datamodel is the conceptual design og the data base.
Some example are

Instance
Instance means complete environment of the database including the RDBMS product tables, schemas, procedures and etc

Domain constraints
Domain constraint are user defind one to restrict
what values a column can hold whether it can hold null and whether it referes to any other column or its a primary key or not.
Example :

Business Rule constrains
Check constraints are one of the business rule contraint which are used to enfore business rule at table level.
Example

Data Dictionary
A data dictionary contains a list of all files in the database, the number of records in each file, and the names and types of each field.

Exampe

Column Name Type Size NULL? PK/FK Constraints
ID    INT  10  NOT  PK  NOT NULL

Views
View are virtual tables which are created by running select query by combining different tables.

Example

CREATE VIEW view_name AS
  SELECT column1, column2, ...
   FROM table_name
  WHERE condition;
Views can be queried in the similar way tables are queried

Transaction
             Transactions are logical unit of work that are executed independently to retrive data from database or to update or insert data into database.
Satisfies ACID - Automicity , Consistancy , Durability , Isolation

Primary Key Attribute
Used to uniquely identify a row in databases table. For example employee Id in employee table.
A table can have only one primary key, which may consist of single or multiple fields.

Eample
CREATE TABLE Persons (
    ID int NOT NULL,
    LastName varchar(255) NOT NULL,
    FirstName varchar(255),
    Age int,
    PRIMARY KEY (ID)
);
Foreign Key Attribute
A FOREIGN KEY is a key used to link two tables.A FOREIGN KEY is a field (or collection of fields) in one table that refers to the PRIMARY KEY in another table.

CREATE TABLE Orders (
    OrderID int NOT NULL PRIMARY KEY,
    OrderNumber int NOT NULL,
    PersonID int FOREIGN KEY REFERENCES Persons(PersonID)
);

Unique Key Attribute
The UNIQUE constraint ensures that all values in a column are different.
A PRIMARY KEY constraint automatically has a UNIQUE constraint.
CREATE TABLE Persons (
    ID int NOT NULL UNIQUE,
    LastName varchar(255) NOT NULL,
    FirstName varchar(255),
    Age int
);
Aggregate function
Aggregate functions perform a calculation on a set of values and return a single value.

Online Analytical Processing
allows users to analyze database information from multiple database systems at one time which are distributed over the network

Example :

Parametric End user
             Errors caused by naive user .

Sophisticated end user
              Errors caused by developers, who write SQL queries to select/insert/delete/update data

Casual end user
                Error created by the user who just wanted to complete the job

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