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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
Difference between cin and scanf?
the getchar function waits the user hit a key followed by return key. Upon the return key hitted by the user the function returns the key. But the scanf can be used for various & different user entered data including text, integer, float and so on. in spite of getchar the delimeter keys for scanf function are tab, space and return key; so when a space entered by the user in the input the scanf will end the input and waits user enter the return key. You must take in mind that just the fragment of input that is behind these delimeters will be considered as legal input for the scanf and the remaninder will be escaped.
ULLS-A (E) is the standard army management information system that allows users to create hand receipts, requisition property, and make property-related administrative adjustments. ULLS-A (E) stands for Unit Level Logistics System-Aviation (Enhanced).
If the keys are expected to be unique then yes. Otherwise no.
What are the differences between blob clob and memo in Oracle?
BLOB is for large Binary based object
Clob is for large Character based object
When should you create a role in Oracle?
I think role is for these two purposes.
1>to grant a group of related privileges to a user
2>to simplify the process of granting and revoking privileges
What six columns are shown in the output of the DESCRIBE table statement?
- Field
Name of the table field.
- Type
Column type such as varchar or timestamp.
- Null
Does the field allow null values?
- Key
Is this field a primary key or (a part of) and index?
- Default
Default field value.
- Extra
Additional information such as "on update CURRENT_TIMESTAMP"
What is a Checkpoint in oracle?
A checkpoint performs the following three operations:
- Every dirty block in the buffer cache is written to the data files. That is, it synchronizes the datablocks in the buffer cache with the datafiles on disk.
It's the DBWR that writes all modified databaseblocks back to the datafiles.
- The latest SCN is written (updated) into the datafile header.
- The latest SCN is also written to the controlfiles.
The update of the datafile headers and the control files is done by the LGWR(CKPT if CKPT is enabled). As of version 8.0, CKPT is enabled by default.
Who invented the first search engine?
Archi is considered to be the first Search Engine in the world.
From Wikipedia:
http://en.wikipedia.org/wiki/Archie_search_engine
"Archie is a tool for indexing FTP archives, allowing people to find specific files. It is considered to be the first Internet search engine.[1] The original implementation was written in 1990 by Alan Emtage, Bill Heelan, and J. Peter Deutsch, then students at McGill University in Montreal."
If it is the first Web-search engine (with websites instead of FTP's) then the answer is Wandex.
From Wikipedia:
http://en.wikipedia.org/wiki/Web_search_engine
"The first Web search engine was Wandex, a now-defunct index collected by the World Wide Web Wanderer, a web crawler developed by Matthew Gray at MIT in 1993. Another very early search engine, Aliweb, also appeared in 1993. JumpStation (released in early 1994) used a crawler to find web pages for searching, but search was limited to the title of web pages only. One of the first "full text" crawler-based search engines was WebCrawler, which came out in 1994. Unlike its predecessors, it let users search for any word in any webpage, which became the standard for all major search engines since. It was also the first one to be widely known by the public. Also in 1994 Lycos (which started at Carnegie Mellon University) was launched, and became a major commercial endeavor."
What is the cost of installing a hard drive?
The current average price of replacing a hard drive is around 200 dollars. This can be done through major retailers or a private chain.
Compact and repair
Mb is "megabit" where MB is megabyte. Bytes are used typically to denote storage where as bits are used to denote data transfer and are usually shown in Mbps, Mb/s, or megabits per second.
One byte is a binary number consisting of 8 bits. Therefore one byte is equal to 8 bits and one megabyte consists of 8 megabits.
What do you mean by normalization?
This is the process of decomposing unsatisfactory relations into smaller relations.
How do you add one or more fields to a table in oracle?
Use the following sql to add columns to an existing table (NOTE: all new columns will be appended to the end of the record DDL)
alter table
table_name
add
(
column1_name column1_datatype column1_constraint,
column2_name column2_datatype column2_constraint,
column3_name column3_datatype column3_constraint
);
