This tutorial explains the basics of DBMS such as its architecture, data models, basic-to-advanced concepts related to Database Management Systems. A database-management system (DBMS) is a collection of interrelated data and a these goals the modeler must analyze narratives from users, notes from. DATABASE MANAGEMENT SYSTEMS. Tibor Radványi PhD. It was made with support of the TÁMOP/1/A
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О a logically coherent structure (can be characterized as a whole). О some inherent meaning (represents some partial view of a portion of the real world). DataBase Management Systems Lecture Notes. UNIT Data: It is a collection of be stored in the DBMS and how it is likely to be used. The DBA creates the. Engineering Class handwritten notes, exam notes, previous year questions, PDF free download.
Skip to main content. Log In Sign Up. Ran Vijay. What is database? A database is a logically coherent collection of data with some inherent meaning, representing some aspect of real world and which is designed, built and populated with data for a specific purpose. What is DBMS? It is a collection of programs that enables user to create and maintain a database.
Data independence means that "the application is independent of the storage structure and access strategy of data". In other words, The ability to modify the schema definition in one level should not affect the schema definition in the next higher level.
Two types of Data Independence: 1. Physical Data Independence: Modification in physical level should not affect the logical level. Logical Data Independence: Modification in logical level should affect the view level. What is a view? How it is related to data independence?
A view may be thought of as a virtual table, that is, a table that does not really exist in its own right but is instead derived from one or more underlying base table. In other words, there is no stored file that direct represents the view instead a definition of view is stored in data dictionary.
Growth and restructuring of base tables is not reflected in views. Thus the view can insulate users from the effects of restructuring and growth in the database. Hence accounts for logical data independence. What is Data Model? A collection of conceptual tools for describing data, data relationships data semantics and constraints. What is E-R model? This data model is based on real world that consists of basic objects called entities and of relationship among these objects.
Entities are described in a database by a set of attributes. What is Object Oriented model? This model is based on collection of objects. An object contains values stored in instance variables with in the object. An object also contains bodies of code that operate on the object.
These bodies of code are called methods.
Objects that contain same types of values and the same methods are grouped together into classes. What is an Entity? It is a 'thing' in the real world with an independent existence.
What is an Entity type? It is a collection set of entities that have same attributes. What is an Entity set? It is a collection of all entities of particular entity type in the database.
What is an Extension of entity type? The collections of entities of a particular entity type are grouped together into an entity set. What is Weak Entity set? An entity set may not have sufficient attributes to form a primary key, and its primary key compromises of its partial key and primary key of its parent entity, then it is said to be Weak Entity set.
What is an attribute? It is a particular property, which describes the entity. What is a Relation Schema and a Relation? A relation Schema denoted by R A1, A2, A relation is defined as a set of tuples. Let r be the relation which contains set tuples t1, t2, t3, What is degree of a Relation? It is the number of attribute of its relation schema. What is Relationship?
It is an association among two or more entities. What is Relationship set? The collection or set of similar relationships.
What is Relationship type? Relationship type defines a set of associations or a relationship set among a given set of entity types. What is degree of Relationship type? It is the number of entity type participating. A data base schema is specifies by a set of definitions expressed by a special language called DDL. It specifies user views and their mappings to the conceptual schema.
This language is to specify the internal schema. This language may specify the mapping between two schemas.
What is Data Storage - Definition Language? The storage structures and access methods used by database system are specified by a set of definition in a special type of DDL called data storage-definition language. This language that enable user to access or manipulate data as organised by appropriate data model. What is DML Compiler? It translates DML statements in a query language into low-level instruction that the query evaluation engine can understand.
What is Query evaluation engine? It executes low-level instruction generated by compiler. What is DDL Interpreter? It interprets DDL statements and record them in tables containing metadata. What is Record-at-a-time? This retrieve of a record is said to be Record-at-a-time. What is Set-at-a-time or Set-oriented? This retrieve of a record is said to be Set-at-a-time or Set-oriented. What is Relational Algebra? It is procedural query language. It consists of a set of operations that take one or two relations as input and produce a new relation.
What is Relational Calculus? It is an applied predicate calculus specifically tailored for relational databases proposed by E. How does Tuple-oriented relational calculus differ from domain-oriented relational calculus? The tuple-oriented calculus uses a tuple variables i. QUEL 2. The domain-oriented calculus has domain variables i.
What is normalization? It is a process of analysing the given relation schemas based on their Functional Dependencies FDs and primary key to achieve the properties 1. Minimizing redundancy, 2. Minimizing insertion, deletion and update anomalies. What is Functional Dependency? A Functional dependency is denoted by X Y between two sets of attributes X and Y that are subsets of R specifies a constraint on the possible tuple that can form a relation state r of R.
This means the value of X component of a tuple uniquely determines the value of component Y. What is Lossless join property?
It guarantees that the spurious tuple generation does not occur with respect to relation schemas after decomposition. What is 1 NF Normal Form? The domain of attribute must include only atomic simple, indivisible values.
What is Fully Functional dependency? It is based on concept of full functional dependency. A functional dependency X Y is full functional dependency if removal of any attribute A from X means that the dependency does not hold any more.
What is 2NF? What is 3NF? X is a Super-key of R. A is a prime attribute of R. In other words, if every non prime attribute is non-transitively dependent on primary key. What is 4NF? X is a super key. What is 5NF? The join dependency is implied by the set of FD, over R in which the left side is key of R. What is Domain-Key Normal Form? A relation is said to be in DKNF if all constraints and dependencies that should hold on the the constraint can be enforced by simply enforcing the domain constraint and key constraint on the relation.
What are partial, alternate,, artificial, compound and natural key? Partial Key: It is a set of attributes that can uniquely identify weak entities and that are related to same owner entity. It is sometime called as Discriminator. Artificial Key: If no obvious key, either stand alone or compound is available, then the last resort is to simply create a key, by assigning a unique number to each record or occurrence.
Then this is known as developing an artificial key. Compound Key: If no single data element uniquely identifies occurrences within a construct, then combining multiple elements to create a unique identifier for the construct is known as creating a compound key. Natural Key: When one of the data elements stored within a construct is utilized as the primary key, then it is called the natural key. What is indexing and what are the different kinds of indexing? Indexing is a technique for determining how quickly specific data can be found.
Types: 1. Binary search style indexing 2. B-Tree indexing 3. Inverted list indexing 4. Memory resident table 5. Table indexing What is system catalog or catalog relation? How is better known as? A RDBMS maintains a description of all the data that it contains, information about every relation and index that it contains.
This information is stored in a collection of relations maintained by the system called metadata. It is also called data dictionary. What is meant by query optimization? The phase that identifies an efficient execution plan for evaluating a query that has the least estimated cost is referred to as query optimization.
What is durability in DBMS? Once the DBMS informs the user that a transaction has successfully completed, its effects should persist even if the system crashes before all its changes are reflected on disk. This property is called durability. What do you mean by atomicity and aggregation? Atomicity: Either all actions are carried out or none are. Users should not have to worry about the effect of incomplete transactions.
DBMS ensures this by undoing the actions of incomplete transactions. Aggregation: A concept which is used to model a relationship between a collection of entities and relationships. This model was straightforward. It used the concept of mathematical relation which looks like a table.
The term can also refer to the dBase database programming language that first appeared in the dBase product, but which is now available in many other database forms. This damage can occur when your computer crashes, a virus infects, you accidentally reformat a disk that contains precious data, or you experience some other catastrophe of considerable dimension.
And, at some point in your life, you're going to delete a file you really didn't mean to believe me. The next time tragedy strikes, try running one of the many data recovery applications powerful software written specifically for data recovery purposes to see if it can correct the situation. Often these little jewels work magic and save your day-and your files. The term used to refer to a separate piece of software that ran on a central computer in this case, it is more or less synonymous with the term "back-end".
Widely used database engines include Oracle, DB2, and Sybase. Separate front-end software running on your own computer lets you tell the database engine what to do how to sort the data, what data to find , and displays the results of your commands. The simplest way to understand a database is to think of it like a set of 3 x 5 cards.
Since the information is on your computer , though, a dick of the mouse or the stroke of a key can alphabetize those "cards," or find just the names of the people on the cards who live in a certain town, or tell you who owes how much money, and so on. For instance, in a database or a spreadsheet you can apply attributes to each field or cell to customize your document.
As a general attribute, you can choose whether it is to be a text field or a numeric field or perhaps a computed field, whose value the application calculates for you. A relation schema is also known as table schema or table scheme. A relation schema can be thought of as the basic information describing a table or relation. It is the logical definition of a table. Relation schema defines what the name of the table is. This includes a set of column names, the data type s associated with each column.
One of the attributes is called the determinant and the other attribute is called the determined. For each value of the determinant there is associated one and only one value of the determined. These problems are called connection traps.
These problems often occur due to a misinterpretation of the meaning of certain relationships. An entity set that has a primary key is called as Strong entity set.
Although each payment entity is distinct but payment for different loans may share the same payment number. Thus, this entity set does not have a primary key and it is an entity set. Each weak set must be a part of one-to-many relationship set. Each modeling methodology uses its own notation.
All notational styles represent entities as rectangular boxes and relationships as lines connecting boxes. Each style uses a special set of symbols to represent the cardinality of connection. The ER model views the real world as a construct of entities and association between entities. This concept purposed by Dr.
Codd, a researcher of IBM in the year s.