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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 does an object-oriented database compare to a relational database?

object-oriented is index by object with no relationship to each other. Relational db has links to other db that have specific information. Some may have Names.db and relate to address.db and so on.

Explain about exception handling with multiple exception?

Exception handling in Java is done through a try-catch-finally block. The "try" block of code is where you put the code which may throw an exception. The "catch" block of code is where you put the code which will execute after an exception is thrown in the try block. This is often used to display an error message, or to mitigate problems caused by the exception. The "finally" block is where you put code that you want to execute after the try and catch blocks have been processed.

// example code for catching exception while reading from a file

try {

// this line of code can throw a FileNotFoundException

FileReader in = new FileReader("myfile.txt");

// this line of code can throw an IOException

in.read();

} catch(FileNotFoundException ex) { // catch first exception type

System.err.println("Cannot find myfile.txt!");

} catch(IOException ex) { //catch second exception type

System.err.println("Cannot read from myfile.txt!");

} finally { // no matter what we want to close the file, so do it here

// however, this line can also cause an exception, so we need to catch that, too

try {

in.close();

catch(IOException ex) {

// not much we can do about an exception that occurs here

}

}

How many people own a USB flash disk?

There does not appear to be any statistical data regarding how many people still own a USB flash disk. However, over $13 million are estimated to have been sold.

How does a user view differ from a conceptual database?

by telling the professor at ODU homework ?'s are being posted on this website

Difference between number and text type field in ms access?

This is true in any database (Access, Oracle). A number field is technically called a "NUMERIC" field. Only numbers can be inserted into a field that has this designator. A text field is for characters or numbers. It can be a "CHAR" (character), a VARCHAR (characters or numbers). It's basically a way of putting rules on columns--what type of data belongs there.

What is token in computer programming?

In a passage of text, individual words and punctuaton marks are called tokens.the smallest individual unit in a prog is called a token..

Fields tha can contain more than one value in Microsoft access?

This statement is not asking a clear question so I am unable to answer the question effectively. This may be something that you would want to post on a tech based message board to get an accurate answer for what you're looking for.

What are the triggers in dbms?

Trigger is defined as a procedural code that is automatically executed in response of certain events on a particular table or view. It is used to maintain the database integrity.

Example: when a new record is added to the student table, new record should also be created in the tables of the attendance, leave & marks table.

How do you make an efficient search form in Microsoft access where you can search by combining criteria?

create a from with an unbound text box. call this box "search". call the form "search" also

create a query on the table you wish to search and modify the querys design. under the field(s) you what to search type forms![search]![search]

create a form on this query

from the "search" form create a search button that opens the search result form. you could also put this procedure on the after update event on the search box

Why is it a good to use a computer to hold database?

It is a good idea because if you type in one of the answers in the search box it will find all the records with that answer in.

How many types of JDBC driver?

There are four types of JDBC driver:

  1. JDBC - ODBC bridge
  2. Native-API driver
  3. Network-Protocol Driver
  4. Native-Protocol Driver
See related link for more information.

What are some ways a computer processes data?

A computer processes data by sorting, merging and making calculations to add more meaning to it. This is done by the computer's CPU.

What are composite primary keys?

The field (column) in a database table that is indexed and maintains the main sequence of the table. For example, account numbers are typically primary keys. A "composite primary key" is made up of two or more fields (columns) such as region + account number.

Source: Answers.com

What are three useful tools for organizing data?

There are a number of useful tools for organizing data. These include spreadsheets, creating graphs, and creating folders to organize all of your documents.

Give an example of how getchar function is used in C program.?

The getchar() function is used to read a single character from standard input (stdin) and increment the associated file pointer to point to the next character. The return value is an integer which must be cast to a character.

An example demonstrating its usage is shown below.

#include <stdio.h>

int main()

{

char buffer[81];

int i, ch;

for(i=0; (i<80) && ((ch = getchar()) != EOF) && (ch!='\n'); ++i)

{

buffer[i] = (char) ch; // cast input to a character

}

buffer[i] = '\0'; // add null-terminator.

printf( "You entered: %s\n", buffer);

}

Length of data types?

* byte: The byte data type is an 8-bit signed two's complement integer. It has a minimum value of -128 and a maximum value of 127 (inclusive). The byte data type can be useful for saving memory in large arrays, where the memory savings actually matters. They can also be used in place of int where their limits help to clarify your code; the fact that a variable's range is limited can serve as a form of documentation. * short: The short data type is a 16-bit signed two's complement integer. It has a minimum value of -32,768 and a maximum value of 32,767 (inclusive). As with byte, the same guidelines apply: you can use a short to save memory in large arrays, in situations where the memory savings actually matters. * int: The int data type is a 32-bit signed two's complement integer. It has a minimum value of -2,147,483,648 and a maximum value of 2,147,483,647 (inclusive). For integral values, this data type is generally the default choice unless there is a reason (like the above) to choose something else. This data type will most likely be large enough for the numbers your program will use, but if you need a wider range of values, use long instead. * long: The long data type is a 64-bit signed two's complement integer. It has a minimum value of -9,223,372,036,854,775,808 and a maximum value of 9,223,372,036,854,775,807 (inclusive). Use this data type when you need a range of values wider than those provided by int. * float: The float data type is a single-precision 32-bit IEEE 754 floating point. Its range of values is beyond the scope of this discussion, but is specified in section 4.2.3 of the Java Language Specification. As with the recommendations for byte and short, use a float (instead of double) if you need to save memory in large arrays of floating point numbers. This data type should never be used for precise values, such as currency. For that, you will need to use the java.math.BigDecimal class instead. Numbers and Strings covers BigDecimal and other useful classes provided by the Java platform. * double: The double data type is a double-precision 64-bit IEEE 754 floating point. Its range of values is beyond the scope of this discussion, but is specified in section 4.2.3 of the Java Language Specification. For decimal values, this data type is generally the default choice. As mentioned above, this data type should never be used for precise values, such as currency. * boolean: The boolean data type has only two possible values: true and false. Use this data type for simple flags that track true/false conditions. This data type represents one bit of information, but its "size" isn't something that's precisely defined. * char: The char data type is a single 16-bit Unicode character. It has a minimum value of '\u0000' (or 0) and a maximum value of '\uffff' (or 65,535 inclusive).

What is star flake schema?

A starflake schema is a combination of a star schema and a snowflake schema. Starflake schemas are snowflake schemas where only some of the dimension tables have been denormalized. hardkingofflirt@gmail.com

Functions of schema?

The schema (pronounced skee-ma) of a database system is its structure described in a formal language supported by the database management system (DBMS). In a relational database, the schema defines the tables, the fields, relationships, views, indexes, packages, procedures, functions, queues, triggers, types, sequences, materialized views, synonyms, database links, directories, Java, XML schema's and other elements.

Schema's are generally stored in a data dictionary. Although a schema is defined in text database language, the term is often used to refer to a graphical depiction of the database structure.

Hope this helps!

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