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The syntax of a query in relational algebra essentially describes the query evaluation algorithm i.e. SELECT WHERE FROM
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I don't agree with the above answer.
Notice that 'SELECT WHERE FROM' is fragmentary SQL. It does not describe an algorithm, or procedure, for obtaining the desired results. Rather, it describes the characteristics of the desired results and where they might be obtained.
In fact, relational algebra is not inherently procedural. It involves closed collections of objects called relations and a set of permitted operations on these objects.
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Why do you use Linq over SQL Statements?
The extensibility of the query architecture is used in the LINQ project itself to provide implementations that work over both XML and SQL data. The query operators over XML (LINQ to XML) use an efficient, easy-to-use, in-memory XML facility to provide XPath/XQuery functionality in the host programming language. The query operators over relational data (LINQ to SQL) build on the integration of SQL-based schema definitions into the common language runtime (CLR) type system. This integration provides strong typing over relational data while retaining the expressive power of the relational model and the performance of query evaluation directly in the underlying store.
What is the difference in Sql statement of sql and of relation algebra?
In essence, Relational Algebra shows the mathematical manner in which a database management system (DBMS) goes about its job. Through the use of Relational Algebra, we can calculate the most efficient way for a DBMS to interact with the database, e.g. updating records, performing a COUNT of the rows in a table etc. The Relational Algebra for returning the surnames in a table holding details of employees where their salary is greater than 30000 per year, is as follows: SELECTSurname(PROJECTSalary>30000) (The SELECT operator is often a Pi symbol, and the PROJECT operator is often a Sigma symbol) An SQL statement, however, would go something like this: SELECT Surname FROM tblEmployee WHERE Salary>30000 Hopefully you can see the difference. Ultimately, the algebra can be used by mathematicians and DBMS creators to ensure the DBMS works as efficiently as possible in performing tasks required by users. Whilst not really necassary in a small-scale database, clearly in a large, complex database you'll be looking at thousands and thousands of rows that need to be queried, updated etc, so efficiency in getting the data back is very important! An SQL statement may look similar, but there's no real calculation involved here. It is instead a standardised language allowing database administrators and users to give a set of instructions, telling the DBMS (Oracle, MS Access, MySQL etc.) what you want to do to a database, e.g. query it, update it, delete from it, and so on. I hope that answers your question!
What is a relational database query and Explain with an example?
A relational database matches data by using common characteristics found within the data set. The resulting groups of data are organized and are much easier for many people to understand.For example, a data set containing all the real-estate transactions in a town can be grouped by the year each transaction occurred, the sale price, a buyer's last name and so on. Such a grouping uses the relational model (a technical term for this is schema). Hence, such a database is called a "relational database."The software used to do this grouping is called a relational database management system (RDBMS). The term "relational database" often refers to this type of software.Relational databases are currently the predominant choice in storing data like financial records, medical records, personal information and manufacturing and logistical data.
Difference between SQL and OQL?
in some cease both are the same they use query language but in fact the out puts are very deference
What is a correlated query?
Correlated query has a subquery in it which accesses the column name of a table alias which is outside the subquery.
What is Procedural query language?
A procedural language is nothing but what we call relational algebra. Procedural language is just like SQL but with different syntax. In Procedural language for "Select" we use projection and for "where" clause we use selection.
Is a query language procedural language?
isA query language is a procedural language.
Is a query language a procedural language?
isA query language is a procedural language.
What are the benefits of relational data model?
structural independencesimplicityad-hoc query capabilityeasy to designsecurity controlnon procedural access language
What is sql and plsql?
SQL stands for Structured Query Language, and is a computer language designed for writing data manipulation or data management statements against a relational database. PL/SQL stands for Procedural Language/Structured Query Language which is Oracle's proprietary procedural extensions to the SQL language.
How would you classify the relational algebra and relational calculus?
1. Relational algebra operations manipulate some relations and provide some expression in the form of queries where as relational calculus are formed queries on the basis of pairs of expressions. 2. RA have operator like join, union, intersection, division, difference, projection, selection etc. where as RC has tuples and domain oriented expressions. 3. RA is procedural language where as RC is non procedural query system. 4. Expressive power of RA and RC are equivalent. This means any query that could be expressed in RA could be expressed by formula in RC. 5. Any KC formula is translated in Algebric query. 6. There is modification which is easy in queries in RA than the RC. 7 RA formed the mathematical form and have no specificjuer1 language RC also has mathematical form but has one query language QUEL. 8. Relational algebra is easy to manipulate and understand than RC. 9. RA queries are more powerful than the RC. 10. RC are formed WFFs where as RA does not form any formula.
What is an example of a standard query language used in relational databases?
The standard query language for relational databases, as adopted by the American National Standards Institute (ANSI), is SQL, which is generally understood to be an abbreviation for "structured query language."
Describe Procedural query language and non procedural query language in DBMS?
A query language is a language in which a user requests information from the database. These languages are usually on a level higher than that of a standardprogramming language. Query languages can be categorized as either procedural or non procedural.In a procedural language, the user instructs the system toperform a sequence of operations on the database to compute the desired result.In a non procedural language, the user describes the desired information withoutgiving a specific procedure for obtaining that information.
What is quel in dbms?
quel is a QUEry Language used in relational database
What is the difference between QBE and SQL?
Query by Example (QBE) is a database query language for relational databases. A QBE parser parses the search query and looks for the keywords. A more formal query string, in languages such as SQL, is then generated, which is finally executed. However, when compared with a formal query, the results in the QBE system will be more variable.SQL (Structured Query Language) SQL is a set-based, declarative query language, not an imperative language such as C or BASIC. However, there are extensions to Standard SQL which add procedural programming language functionality, such as control-of-flow constructs
What is difference between linear syntax and relational algebra?
They are not alternative solutions so that we can compare them. Relational database (which is based on relational algebra) demands (atleast the founder of relational database Codd suggests) that the query language follow linear syntax. The linear syntax languages don't rely up on newline characters as terminators of expressions or statements -- instead they rely on other tokens such as semicolon or comma and so on.
1 Difference between relational algebra and relation Calculus?
What is the Diff. Between Relational Algebra & Calculas? {| ! width="33%" | Point of Comparison |- ! width="33%" | R.Algebra ! width="33%" | R.Calculus | Is it Query Language ? YES YES Relation Query Describe step-by-step proceduar for computing the desired answer ,depend on the order in which operator are applies in query Describe the set of answer without being excplicit about how they should be computed Type Proceduar Non-proceduar |}
