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Difference between relation and relational schema?
In database design a RELATION is the relationship that you build between two or more tables. As an example lets say you have a Customer table. In this table you have lots of fields FirstName, LastName, Address, City, State, PostalCode, StatusID; etc....... Now StatusID is going to be a numeric value. Lets say that the value is 1 Now you will have a Status Table with multiple fields (ex) StatusID, StatusName, Active, etc..... Now when you display customer information you will not want to show a StatusID as nobody will know what this is. You will want to show the NAME associated with the status. To do this you will create a releationship between StatusID in the Customer table and StatusID in the Status table. In doing so you will provide for faster lookup results, a constraint that does not permit a numeric value in the StatusID field in the customer table that is NOT in the StatusID field of the Status table. THEN... To show correct Results you would write a query something like: SELECT FirstName, LastName, Address, City, State, PostalCode, StatusName FROM Customers as c JOIN Status as s on s.StatusID = c.StatusID A relational Schema is simply a representation of your database highlighting the relationships that you have created throughout.
What are one to many and many to many Relationship in database?
Relationships happen between two tables. One to Many means that one objects (called tuples, or rows) of Table A is related to one or more objects in Table B. For example, if a doctor can work only in one hospital, and we have a table of hospitals and a table of doctors, Hospitals has a One to Many relationship with Doctors, because for each hospital you will have one or more doctors working at it. Many to Many means that for each object in Table A, one or more objects in Table B are associated, and viceversa. In the example, if doctors are allowed to work in different hospitals, the table Hospitals and the table Doctors have a Many to Many relationship. Now, how to implement this in a relationship DB, that is another question.
What is an advantage of using the method of substitution rather than using a graph or table to solve a system of linear equations?
You will obtain a more accurate answer than is possible using graphical methods. It's faster and less work than using a table.
What is the purpose of relating tables in a database?
to calculate data more effectively
What is Relationship between a primary and a foreign key?
A primary key is one or more colums in a table whose values would uniquely identify a row in that table. A foreign key is a one or more columns in one table that are used to reference rows in another table. In a properly designed 3NF schema, the foreign key columns should correspond to the primary key columns of the table being referenced.
In a relational database can two or more tables be liked to appear as one table?
Yes. That is how relational database work.
How many tables are in a relational database?
A table consists of two or more records.
What is RBDMS?
RDBMS stands for Relational Database Management System. RDBMS data is structured in database tables, fields and records. Each RDBMS table consists of database table rows. Each database table row consists of one or more database table fields.RDBMS store the data into collection of tables, which might be related by common fields (database table columns). RDBMS also provide relational operators to manipulate the data stored into the database tables. Most RDBMS use SQL as database query language.
What are typical benefit of relational databases?
With a relational database, you can quickly compare information because of the arrangement of data in columns.A typical relational database has anywhere from 10 to more than 1,000 tables. Each table contains a column or columns that other tables can key on to gather information from that table.By storing this information in another table, the database can create a single small table with the locations that can then be used for a variety of purposes by other tables in the database. A typical large database, like the one a big Web site, such as the police would have, will contain hundreds or thousands of tables like this all used together to quickly find the exact information needed at any given time
What are the typical benefits of relational databases?
With a relational database, you can quickly compare information because of the arrangement of data in columns.A typical relational database has anywhere from 10 to more than 1,000 tables. Each table contains a column or columns that other tables can key on to gather information from that table.By storing this information in another table, the database can create a single small table with the locations that can then be used for a variety of purposes by other tables in the database. A typical large database, like the one a big Web site, such as the police would have, will contain hundreds or thousands of tables like this all used together to quickly find the exact information needed at any given time
Are there any major similiarities between object oriented databases and relational databases?
In a Object Oriented Database, information is given in the form of objects as used in programming languages. "When database capabilities are combined with object programming language capabilities, the result is an object database management system (ODBMS). An ODBMS makes database objects appear as programming language objects in one or more object programming languages." (http://en.wikipedia.org/wiki/Object_database)"A relational database is a database that conforms to the relational model, and refers to a database's data and schema (the database's structure of how those data are arranged). Common usage of the term "Relational database management system" technically refers to the software used to create a relational database, but sometimes mistakenly refers to a relational database." (http://en.wikipedia.org/wiki/Relational_database)
What is a table in a database for?
Tables are used to provide reference to comparative data when individual comparisons are not possible or preferable. In a database, a table provides the value associated with two (or more) separate inputs.
What is a database in which ALL the data is stored in a single table known as?
A database in which ALL the data is stored in a single table is known as a flat-file database. This type of database lacks the relational structure found in more traditional databases that use multiple tables to store and organize data. Flat-file databases are simple but may limit the ability to efficiently query and manage data.
How are field record table and relational database relate to one another in Access?
A table stores data. Tables have fields in them, like name, address, date of birth etc. They are often likened to columns. One individual set, like your name, address and date of birth is a record. So tables have records in them. In a relational database there is more than one table and these tables are related to each other. So one table might store all your personal details and another my store all your employment details. By having at least one common field, like an employee number, these two tables can be related to each other. Access is a database application and has the capability to create relational databases.
Why should we relate tables?
The relational database model tends to be far more flexible than other models such as hierarchical. It also provides better data security, since user access can be limited by the table or even the field within a table.
A relational database consists of how many tables?
A relational DB can consist of any number of tables. --------------- Two or more tables to establish a relationship. You cannot have a relationship with yourself ...
What are the disadvantages of normalizing a table in a database?
All databases tend to be normalized to some degree; in fact, a relational database almost must adhere to a minimum of 1NF to be useful. However, the more a database is normalized, the greater the impact of processing time of queries is likely to be. For one thing, higher levels of normalization results in larger numbers of decode tables and the like, requiring more table joins in retrieval queries and more referential integrity overhead.
