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Database Programming
Databases are collections of tables that maintain and display information, often collaboratively; this information can be used for interaction with an application or gaining general knowledge. Questions about database engines and modifying or using them belong in this category.
8,803 Questions
How many super keys are possible in DBMS having m attributes?
In dbms with m attributes 2^m-1 keys are possible.
BY-ROHIT
How do you create a one-to-many relationship in a database system?
There are usually two ways in how you can create a one-to-many relationship, either using the Structured Query Language (SQL) or by using a graphical managament tool like the MS Access interface, Sql Server Management Studio (for Sql Server) or Sql Yog (for Mysql).
SQL is the most common way to create a one-to-many relationship in a database.
Create a one-to-many relationship using SQLCREATE TABLE Customers (
customer_id INT PRIMARY KEY,
first_name VARCHAR(30) NOT NULL,
last_name VARCHAR(30) NOT NULL
)
Then, create another table with a primary key AND a foreign key that references the primary key of the Customers table.
CREATE TABLE Orders(
order_id INT PRIMARY KEY,
order_date DATE NOT NULL,
customer_id INT NOT NULL,
FOREIGN KEY(customer_id) REFERENCES Customers(customer_id)
)
The important part is the FOREIGN KEY declaration in the Orders table. It says that the customer_id in the Orders table is a reference to the customer_id primary key field in the Customers table. Each Order is linked to a (one) Customer in this way and each Customer can be linked to multiple (many) orders, because multiple records in the Orders table can have the same customer_id.
Creating a one-to-many relationship in MS AccessPrograms that have a large emphasis on the graphical user interface like Microsoft Access will let you create relationships in a graphical environment. In Microsoft Access you can create a one-to-manyby dragging tables into the relationships screen and dragging the primary key of one table onto the designated foreign key counterpart in another table.
In Access you can get to the Relationships screen by going to the Database tools tab and clicking the Relationships button next.
What are the advantages and disadvantages of file based systems?
File-based systems are low cost and do not need external storage or somebody that is extremely knowledgeable in technology. Disadvantages include data duplication, lack of flexibility, and a lack of security.
What is the main advantage of the microkernel approach to system design?
Microkernels provide minimal process and memory management, in addition to a communication facility.
How do you run PHP in Windows without SQL?
Install Apache server.
The best solution is to install the latest version of WAMP server (Windows Apache MySQL PHP). You can then open the WAMP folder on your hard drive and locate the WWW folder. Inside of the WWW folder you can store your PHP files.
To preview the files open a browser and enter 'http://localhost' to test if the server is working, after testing add the name of a PHP file to the URL, 'http://localhost/myFile.php'.
Inner circuit diagram view of the intelligance library management system by using RFID
The correct syntaxt would be:
(local)\FLIPINSTANCE
It is hard to answer without a context, as in when and where are you getting this error.
History of database management system?
top 10 significant people,event,history development in database management system
Candidate key and primary key differnece?
All Primary keys are definitely Candidate Keys. A Candidate key is one which can be used as a Primary key that is not null and unique. That is one of the candidate keys can be chosen as a primary key.A Candidate key is a Unique Key and it can be used to find out any particular Tuple (row) in a table.
The following are the differences between A Candidate key and a Primary Key:
1) A Unique key can be null but not a Primary key
2) On a table we can have only 1 primary key but 'N' number of unique keys.
Explain why a primary key is a field which uniquely identifies the record?
A database table will, under normal circumstances, have more than one column. So, assuming that there is a table of say, employees in a company, the table could look like First_name
Last_name
Date_of_Birth
The columns above could be duplicated if there are employees ...
Bill,Sykes,12 April 1977
Bill,Cody, 13 April 1977
Fred,Cody,14 April 1977
Fred,Sykes,15 April,1977
Henry,Smith,12 April 1977
As can be seen above First_name is duplicated with Bill and Fred - no good for a unique primary key. The same applies to Cody/Sykes and 12 April 1977.
At this point, it would be a good idea to bring in another column, say Employee_number, where each employee has a unique payroll number. This could be the unique primary key, only occurring once in the table.
It is possible to have a unique key spanning multiple columns, but that will bring extra overheads with indexing.
List six major steps that you would take in setting up a database for a particular?
1. Requirement Analysis
2. Conceptual Data Base Design
3. Logical Data Base Design
4. Schema Refinement
5. Physical Data Base Design
6. Security Design
Can you create a program using SQL?
No you can't. SQL is not a programming language, so it doesn't create programs. It is a query language, and it creates queries. There is a difference. There are various things that programming languages have and that they can do, which would take a more detailed explanation to define. SQL is very limited in what it can do, being specifically designed to work with data and manipulate databases. It does not have the capabilities of a programming language. A query and a program are both a list of commands to do a task, but a program is far more extensive and can do far more things, and so it is very different to a query.
Advantages and disadvantages of External database?
Dis Advantages: Security may be compromised without good controls, Extra hardware may be required, System is likely to be complex Advantages: Reduced data redundancy, Secured data, Integrated data, Controlled data inconsistency
How a primary key is fixed in a sql table?
A primary key field in a sql table is created using the PRIMARY KEY keyword. ex:
CREATE TABLE tbl_employee (
emp_num VARCHAR(10),
emp_name VARCHAR(100),
PRIMARY KEY (emp_num))
The above script creates a table called tbl_employee and sets the emp_num field as the primary key
What are the task performed by Database management system?
1. it helps each application program to be executed in a sequence.
2. it requests the operating systems to execute an input operation.
3. it provides status information to the application program.
4. It processes data.
- RIYA G.
What is the difference between greedy algorithm and Divide and Conquer?
greedy method does not give best solution always.but divide and conquer gives the best optimal solution only(for example:quick sort is the best sort).greedy method gives feasible solutions,they need not be optimal at all.divide and conquer and dynamic programming are techniques.
Databases organize information into records, each of which represents a single unit of information
In transaction management how do you match a transaction to an order?
Search a selected transaction, then search and select the order, then click the match to transaction button to match a transaction to an order.
Data validation best refers to?
Data Validation is a process that ensures that data entered into the database form, a web form, or a computer program conforms to the correct data type.
How do you make E-R diagram for sending online greeting cards system?
E-R diagram for prepering greeting cards
Normalization is the process of efficiently organizing data in a database. There are two goals of the normalization process: eliminating redundant data (for example, storing the same data in more than one table) and ensuring data dependencies make sense (only storing related data in a table). Both of these are worthy goals as they reduce the amount of space a database consumes and ensure that data is logically stored.
