no diff between varchar and varchar2
char store only chacter type but varchar2 store variable chacters.
also varchar2 shirinks the space if not fully filled but char cant.
difference between relation sehema and relation instance in dbms
Essbase is a multidimensional DBMS where Hyperion performance suite is a set of BI tools.
Many to many relationship in DBMS is usually a mirror of the real-life relationship between objects that tables represent.
As I understand it, a database schema is a physical entity, it describes the structure of exactly how the data is stored and is itself stored by DBMS for reference. Data model, on the other hand, is an abstract representation of database.
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!
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I'm Looking for the Same awnser. anyone? Thank
database approach
difference between relation sehema and relation instance in dbms
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Traditional FPS and DBMS both are different from each other. In DBMS there is security of data as well as integrated data while this is not in FPS.
A Homogeneous database will have only one DBMS, while heterogeneous databases have multiple DBMS's
A DBMS is a database management system. A database application would be something inside the DBMS such as: ~a way to search files ~a way to pull certain information
save point saves the dbms and check point simply check the database thats it simple
dbms stands for database management system and this mdbms is mulivalue database management system. if we need to store the a multidata then we have to use the mdbms
create table vino(char name(6));
A DBMS stores data in a table where the entries are filed under a specific category and are properly indexed. This allowed programmers to have a lot more structure when saving or retrieving data. A relational database contains data in more than one table. Each table contains a database that is then linked to other tables with respect to their relationships. Read more: Difference Between DBMS and RDMS | Difference Between | DBMS vs RDMS http://www.differencebetween.net/technology/difference-between-dbms-and-rdms/#ixzz1eJUZkRgz