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Articles by Bhanu Priya
Page 75 of 106
What are the most used SQL clauses in DBMS?
SQL is a Structured Query Language which is the standard and most widely used programming language for relational databases. It is used to manage and organize data in all sorts of systems where all varieties of data relationships exist.Structured Query Language (SQL) ClausesThe SQL clauses are of three types as shown below−Let us learn about them one by one.GROUP BY CLAUSESQL GROUP BY is used to arrange identical data into groups. It is used with the SQL SELECT statement. The GROUP BY statement follows the WHERE clause in a SELECT statement and precedes the ORDER BY clause. It is also ...
Read MoreExplain the difference between a table, view and synonym in SQL
Let us understand what table, view and synonym in the structured query language (SQL) are.Table, view and synonymA table is a repository of data, where in the table it is a physical entity. A table resides physically in the database.A view is not a part of the database’s physical representation. It is precompiled, so that data retrieval behaves faster and also provides a secure accessibility mechanism.A synonym is an alternate name assigned to a table, view, sequence or program unit.ExampleCreate table employee (empID integer primary key, name varchar2(30), skill varchar2(30), salary number(20), DOB datetime).Let’s say there is a scenario where ...
Read MoreExplain the concept of the traditional file system in DBMS?
A file system is a method of storing and organizing the computer files and the data they contain to make it easy to find and access them.Characteristics of file systemThe characteristics of file system are as follows −It is a group of files for storing the data of an organization.Each file is independent from one another.Each file is called a flat file.Files are designed by using the program written in programming languages such as C, C++.Disadvantages of file processing systemThere are so many disadvantages in the file processing system. These are explained below −Separated and isolated data.Duplication of data − ...
Read MoreWhat is the difference between data and information in DBMS?
Before understanding the difference between data and information, let’s have a look at the definitions of data and information with an example.DataData is the raw material that can be processed for any computing machine.For example − Employee name, Product name, Name of the student, Marks of the student, Mobile number, Image etc.InformationInformation is the data that has been converted into more useful or intelligent form.For example: Report card sheet.The information is needed for the following reasons −To gain knowledge about the surroundings.To keep the system up to date.To know about the rules and regulations of the society.KnowledgeThe human mind purposefully ...
Read MoreDistinguish between flat files and databases (dbms)?
Let’s discuss flat and database definition before understanding the difference between flat files and databases.Flat filesA flat file contains records which have no structured interrelationship. They are typically called as a text file, where all word processing, structure characters and markup have been removed. A flat file represents a table with a single record per line. Generally, it is a type of database that stores data in a plain text format.DatabaseThe related information when placed in an organized form that makes a database or an organized collection of related information is called a database.For example − Dictionary, Telephone directory etc.DifferencesFollowing ...
Read MoreHow to generate regular expression from finite automata?
There are two methods for converting deterministic finite automata (DFA) to Regular expression (RE). These are as follows −Arden’s MethodState Elimination MethodLet us understand these methods in detail.Arden’s TheoremLet P and Q be the two regular expressions.If P does not contain null string, then following equation in R, viz R = Q + RP,Which has a unique solution by R = QP*Here,The finite Automata do not have epsilon movesIt must have only initial state q1It’s states are q1, q2, q3,…….qn. The final state may be some qi where i
Read MoreProve that Linear bounded automata LBA ⊂ PSPACE in TOC?
Linear Bounded Automaton (LBA) is a restricted form of Turing Machine in which input tape is finite.ExampleProve that LBA ⊂ PSPACEPSPACE is a superset of the set of context-sensitive languages.Now to prove LBA=PSPACE, We use theorem of Space compression with tape reduction which states that, For every k-tape S(n) space-bounded off-line Turing Machine M and constant c>0, there exists a one-tape cS(n) space-bounded off-line turing machine N such that L(M)=L(N).Following identity holds for −DSPACE(S(n))=DSPACE(O(S(n)))and NSPACE(S(n))=NSPACE(O(S(n)))Since LBA is one-tape n space-bounded Turing Machine it follows −LBA=NSPACE(n)---------------------(1)Now by Savitch theorem, if S is fully space constructible and S(n)>log(n) thenNSPACE(S(n)) ⊆DSPACE(S^{2}(n)) -------------(2)Final proofLBA=NSPACE(n)............by(1)⊆DSPACE(n^{2})............by(2)⊂DSPACE(n^{3})............by ...
Read MoreConstruct a PDA that accepts (a,b)* language but not contain bbbb?
Push down Automata (PDA) is complement of the PDA that contain Substring bbbStepsMake the PDA for accepting those strings that have conation bbb.Complement it by making non-accepting as accepting and vice versa.Construct PDAYou can construct the PDA as shown below for the (a, b)* languageThe nature of transition format is Input, Top of stack, PUSH/POPExamplea ,a , aa means on i/p a and top of stack is a then push aAt q0 i, e initial if a or b anything came move state to q1Till q1 we get 1 b to make substring b_ _ so now on q1 if ...
Read MoreConstruct a TM that accepts even-length palindromes over the alphabet {0,1}?
A Turing machine (TM) is a 7-tuple (Q, ∑, Γ, δ, q0, qaccept , qreject).Where, Q is a finite set of states.∑ is the input alphabet that does not contain the blank symbol t.Γ is the tape alphabet, where t ∈ Γ and ∑ ⊆ Γ.δ: (Q × Γ) → (Q × Γ × {L, R}) is the transition function.q0 ∈ Q is the start state.qaccept ∈ Q is the accept state.qreject ∈ Q is the reject state, where qreject ≠ qaccept.For accepting even-length palindrome over the alphabet {0, 1}, follow the steps given below −Match the first and last ...
Read MoreConstruct a TM for a binary number as an input and replace the last digit with its Boolean complement?
ProblemDesign a TM (Turing Machine) that takes a binary number as an input and replaces the last digit of the string with its Boolean complement.SolutionA Turing machine is a 7-tuple (Q, ∑, Γ, δ, q0, qaccept , qreject)Where, Q is a finite set of states.∑ is the input alphabet that does not contain the blank symbol t.Γ is the tape alphabet, where t ∈ Γ and ∑ ⊆ Γ.δ − (Q × Γ) → (Q × Γ × {L, R}) is the transition function.q0 ∈ Q is the start state.qaccept ∈ Q is the accept state.qreject ∈ Q is the ...
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