DBMS Unit 1 $2 Short Notes

1.1. What are the functions of DBMS? Ans. The functions of DBMS are i. The capability to modernize and recoup data ii. Support concurrent updates iii. Recovery of data iv. Security Data integrity . List some operations of DBMS. Ans. operations of DBMS are Banking ii. Airlines iii. Credit card deals iv. Finance Web grounded services vi. Telecommunications . What are the advantages of train processing system which were removed by the DBMS? Ans. No problem of centralization ii. Less precious iii. lower need of tackle iv. Less complex in backup and recovery . What’s data model? List the types of data model used. Ans. Data model is a logical structure of the database. It’s a collection of abstract tools for describing data, data connections, data semantics and thickness constraints. Types of data model used 1. Hierarchical model 2. Network model 3. Relational model 4. Object- acquainted model 5. Object- relational model . Write advantages of database. Ans. Advantages of database 1. Controlling data redundancy 2. participating of data 3. Data thickness 4. Integration of data 5. Integration constraints 6. Data security . Explain logical data independence. Ans. The separation of the external views from the abstract views which enables the stoner to change the abstract view without effecting the external views or operation program is called logical data independence . Define the term data redundancy and data thickness. Ans. Data redundancy The circumstance of values for data rudiments further than formerly within a train or database is called data redundancy. Data thickness Data thickness states that only valid data will be written to the database. . What do you mean by DML and DDL? OR Define DML. Ans. Data Manipulation Language( DML) A DML is a language that enables druggies to pierce and manipulate data as organized by the applicable data model. fit, modernize, cancel, query are generally used DML commands. Data Definition Language( DDL) DDL is set of SQL commands used to produce, modify and cancel database structures but not ‘re typically used by the DBA. produce, drop, alter, truncate are generally used DDL command. . Give illustration of a simple, compound attributes of an reality. Ans. Simple trait A simple trait is an trait composed of a single element with an independent actuality. Example Roll number, paymentetc. compound trait An trait composed of multiple factors each with an independent actuality is called a compound trait. illustration Name, which is composed of attributes like first name, middle name and last name. . Describe the purpose of foreign key. Ans. A foreign key is used to link tables together and produce a relationship. It’s a field in one table that’s linked to the primary key in another table. . Explain specialization. Ans. Specialization is the abstracting process of introducing new characteristics to an being class of objects to produce one or further new classes of objects. This involves taking a advanced- position, and using fresh characteristics, generating lower- position realities. . What do you mean by aggregation? Ans. Aggregation is an abstraction through which connections are treated as advanced position realities. . Define super crucial, seeker key, primary key and foreign key. Ans. Super crucial It’s a set of one or further attributes that, taken inclusively, allows us to identify uniquely an reality in the reality set. seeker key A seeker key is a column, or set of column, in the table that can uniquely identify any database record without pertaining to any other data. Primary crucial Primary key is a seeker key that’s used for unique identification of realities within the table. Foreign key A foreign key is deduced from the primary key of the same or some other table. Foreign key is the combination of one or more columns in a table( parent table) at references a primary crucial in another table( child table). . What’s strong and weak reality set? Ans. Strong reality Strong reality isn’t dependent of any other reality in schema. Strong reality always has primary key. Strong reality is represented by single cube. Two strong reality‚Äôs relationship is represented by single diamond. Weak reality Weak reality is dependent on strong reality to insure the actuality of weak reality. Weak reality doesn’t have any primary key, it has partial discriminator key. Weak reality is represented by double cube. 2UNIT . Define the term degree and cardinality. Ans. Degree The number of attributes in a relation is known as degree. Cardinality The number of tuples in a relation is known as cardinality. . What do you mean by referential integrity? AKTU 2015- 16, Marks 02 Ans. In the relational model, for some cases, we frequently wish to insure that a value that appears in one relation for a given set of attributes also appears for a certain set of attributes in another relation. This condition is called as referential integrity. . Explain reality integrity constraints. Ans. The reality integrity constraint states that primary keys can not be null. There must be a proper value in the primary crucial field. This is because the primary crucial value is used to identify individual rows in atable.However, it would If there were null values for primary keys. mean that we couldn’t identify those rows. . Define foreign crucial constraint. Ans. A foreign crucial constraint allows certain attributes in one relation to relate to attributes in another relation. The relation on which foreign crucial constraint is defined contains the partial information. . With an illustration show how a referential integrity can be enforced. Ans. This rule states that if a foreign key in Table 1 refers to the primary key of Table 2, also every value of the foreign key in Table 1 must be null or be available in Table 2. . When do you get constraints violation? Also, define null value constraint. Ans. Constraints get violated during update operations on the relation. Null value constraint While creating tables, if a row lacks a data value for a particular column, that value is said to be null. . What’s the part of join operations in relational algebra? Ans. The join operation, denoted by, is used to join two relations to form a new relation on the base of a common trait present in the two operand relations. . What are characteristics of SQL? Ans. Characteristics of SQL 1. SQL operation is extremely flexible. 2. It uses a free form syntax . Give graces and faults of SQL database. Ans. graces of SQL database High speed ii. Security iii. comity iv. No coding needed faults of SQL database i. Some performances of SQL are expensive. ii. Difficulty in uniting iii. Partial control is given to database. . What’s the purpose of view in SQL? Ans. A view is a virtual relation, whose contents are deduced from formerly being relations and it doesn’t live in physical form. A view can be used like any other relation, which is, it can be queried, fitted into, deleted from and joined with other relations or views, though with some limitations on update operations. . Which command is used for creating stoner- defined data types? Ans. The stoner- defined data types can be created using the CREATE sphere command. . What do you mean by query and subquery? Ans. Query is a request to database for carrying some data. A subquery is a SQL query nested inside a larger query. Subqueries must be enclosed within gap. . Write the purpose of detector. Ans. Purpose of detector 1. Automatically induce deduced column values. 2. help invalid deals. 3. apply complex security authorizations. 4. apply referential integrity across bumps in a distributed database. 5. apply complex business rules. . What do you mean by PL/ SQL? Ans. PL/ SQL stands for Procedural Language SQL. PL/ SQL extends SQL by adding constructs set up in procedural languages, performing is a structural language that’s more important than SQL. . What’s union comity? Ans. Two relation cases are said to be union compatible if the following conditions hold They’ve the same number of the fields. ii. Corresponding fields, taken in order from left to right, have the same disciplines. . What’s Relational Algebra? Ans. The relational algebra is a procedural query language. It consists of a set of operations that take one or two relations as input and produces a new relation as a result. . Define constraint and its types in DBMS. Ans. A constraint is a rule that’s used for optimization purposes. Types of constraints 1. NOT NULL 2. UNIQUE 3. dereliction 4. CHECK 5. crucial constraints Primary crucial ii. Foreign crucial 6. sphere constraints

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