DBMS Unit-1 Part-3 Introduction

Que1.15. Compactly describe the overall structure of DBMS. OR Draw the overall structure of DBMS and explain its factors in Answer A database system is partitioned into modules that deal with each of the liabilities of the overall system. The functional factors of a database system can be astronomically divided into two factors 1. Storage Manager( SM) A storehouse director is a program module that provides the interface between the low position data stored in the database and the operation programs and queries submitted to the system. The SM factors include Authorization and integrity director It tests for the satisfaction of integrity constraints and checks the authority of druggies to pierce data. sale director It ensures that the database remains in a harmonious state despite of system failures and that concurrent sale prosecutions do without clashing. train director It manages the allocation of space on fragment storehouse and the data structures are used to represent information stored on fragment. Buffer director It’s responsible for costing data from fragment storehouse into main memory and deciding what data to cache in main memory. The buffer director is a critical part of the database system, since it enables the database to handle data sizes that are much larger than the size of main memory. 2. Query Processor( QP) The Query Processor( Query Optimizer) is responsible for taking every statement transferred to SQL Garçon and figure out how to get the requested data or perform the requested operation. The QP factors are DDL practitioner It interprets DDL statements and records the description in data wordbook. DML compiler It translates DML statements in a query language into an evaluation plan conforming of low- position instructions that the query evaluation machine understands. Query optimization It picks the smallest cost evaluation plan from among the druthers
. Query evaluation machine It executes low- position instructions generated by the DML compiler. Que1.16. What’s ER model? What are the rudiments of ER model? OR What are the memos of ER illustration? Answer An reality relationship model( ER model) is a way of representing the realities and the connections between the realities in order to produce a database. rudiments/ memorandum of ER model/ illustration 1. reality a. An reality is a real world object that can be fluently identifiable. b. An reality can be abstract. c. An reality is an object that exists and is distinguishable from other objects. 2. reality set reality set is a collection of analogous type of realities. b. An reality set may contain realities with trait sharing analogous values. 3. Attribute a. An trait gives the characteristics of the reality. It’s also called as data element, data field, a field, a data item, or an abecedarian item. 4. Relationship a. A relationship is the association between realities or reality circumstance. Relationship is represented by diamond with straight lines connecting the realities. Que13.17. What do you understand by attributes and sphere? Explain colorful types of attributes used in abstract data model. Answer Attributes 1. Attributes are parcels which are used to represent the realities. 2. All attributes have values. For illustration, a pupil reality may have name, class, and age as attributes. 3. There exists a sphere or range of values that can be assigned to attributes. 4. For illustration, a pupil’s name can not be a numeric value. It has to be alphabetic. A pupil’s age can not be negative,etc. sphere 1. A sphere is an trait constraint which determines the type of data values that are permitted for that trait. 2. trait disciplines can be veritably large, or veritably short. Types of attributes used in abstract data model 1. Simple trait Simple attributes are infinitesimal values, which can not be divided further. For illustration, a pupil’s phone number is an infinitesimal value of 10 integers. 2. compound trait compound attributes are made of further than one simple trait. For illustration, a pupil’s complete name may have andlast_name. 3. deduced trait deduced attributes are the attributes that do not live in the physical database, but their values are deduced from other attributes present in the database. For illustration,average_salary in a department shouldn’t be saved directly in the database, rather it can be deduced. 4. Single- value trait Single- value attributes contain single value. For illustration,Social_Security_Number. 5. Multi-value traitMulti-value attributes may contain further than one values. For illustration, a person can have further than one phone number,email_address,etc. Que1.18. What’s purpose of the ER illustration? Construct an ER illustration for a University system which should include information about scholars, departments, professors, courses, which scholars are enrolled in which course, which professors are tutoring which courses, pupil grades, which course a department offers. Answer Purpose of the ER illustration 1. ER illustration is used to represent the overall logical structure of the database. 2. ER plates emphasis on the schema of the database and not on the cases because the schema of the database is changed infrequently. 3. It’s useful to communicate the logical structure of database to end druggies. 4. It serves as a attestation tool. 5. It helps the database developer in understanding the information to be contained in the database. Que1.21. Describe mapping constraints with its types. OR Describe mapping constraints with its types. AKTU 2019- 20, Marks 07 Database Management System 1 – 21 A( CS/ IT- Sem- 5) Answer 1. Mapping constraints act as a rule followed by contents of database. 2. Data in the database must follow the constraints. Types of mapping constraints are 1. Mapping cardinalities Mapping cardinalities( or cardinality rates) specifies the number of realities of which another reality can be associated via a relationship set. Mapping cardinalities are used in describing double relationship sets, although they contribute to the description of relationship sets that involve further than two reality sets. c. For double relationship set R between reality sets A and B, the mapping cardinality must be one of the following i. One to one An reality in A is associated with at most one reality in B and an reality in B is associated with at most one reality inA. ii. One to numerous An reality in A is associated with any number of realities in B. An reality in B, still, can be associated with at most one reality inA. iii. numerous to one An reality in A is associated with at most one reality in B, and an reality in B, still, can be associated with any number of realities inA. iv. numerous to numerous An reality in A is associated with any number of realities in B, and an reality in B is associated with any number of realities inA. 2. Participation constraints It tells the participation of reality sets. There are two types of participations Partial participation ii. Total participation Que1.22. bandy the seeker key, primary key, super key, compound key and alternate key. OR Explain the primary key, super key, foreign key and seeker key with illustration. OR Define key. Explain colorful types of keys. Answer 1. Key is a trait or set of attributes that’s used to identify data in reality sets. 2. Key is defined for unique identification of rows in table. Consider the following illustration of an Hand table Hand( EmployeeID, FullName, SSN, DeptID) colorful types of keys are 1. Primary crucial Primary crucial uniquely identifies each record in a table and must noway , be the same for records. Then in Hand table we can choose either EmployeeID or SSN columns as a primary key. Primary key is a seeker key that’s used for unique identification of realities within the table. Primary key can not be null. Any table has a unique primary key. 2. Super crucial a. A super key for an reality is a set of one or further trait whose concerted value uniquely identifies the reality in the reality set. b. For illustration Then in hand table( EmployeeID, FullName) or EmployeeID, FullName, DeptID) is a super key. 3. seeker crucial a. 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. seeker key are individual columns in a table that qualifies for oneness of all the rows. Then in Hand table EmployeeID and SSN are seeker keys. minimum super keys are called seeker keys. 4. Composite crucial a. A compound key is a combination of two or further columns in a table that can be used to uniquely identify each row in the table. It’s used when we can not identify a record using single attributes. c. A primary key that’s made by the combination of further than one trait is known as a compound key. 5. Alternate crucial a. The alternate key of any table are those seeker keys which are not presently named as the primary key. Exactly one of those seeker keys is chosen as the primary crucial and the remainders, if any are also called alternate keys. c. An alternate key is a function of all seeker keys minus the primary key. d. Then in Hand table if EmployeeID is primary key also SSN would be the alternate key. 6. Foreign crucial Foreign key represents the relationship between tables and ensures the referential integrity rule. b. A foreign key is deduced from the primary key of the same or some other table. Foreign key is the combination of one or further columns in a table parent table) at references a primary key in another table( child table). d. A foreign crucial value can be left null. For illustration Consider another table design( ProjectName, TimeDuration, EmployeeID) Then, the ‘ EmployeeID ’ in the ‘ Project ’ table points to the ‘ EmployeeID ’ in ‘ Employee ’ table b. The ‘ EmployeeID ’ in the ‘ Hand ’ table is the primary key. c. The ‘ EmployeeID ’ in the ‘ Project ’ table is a foreign key.

Leave a Comment