Database Programming

'Stored program' was the breakthrough that enabled computers to perform complex tasks in fractions of a second. Being able to do arithmetic and evaluate formulas fast would be useless if a person had to keep telling the computer what to do next. The trick was encoding the list of instructions into numbers that could coexist in the computer's memory along with data, and having a 'processor' built into the machine to decode and execute the instructions. Now the computer could do both, calculate and control the sequence of calculations, at electronic speed.

Many credit John von Neumann with devising the stored program concept, but probably several others were also involved.

Manage data and databases.

The information system (IS) consists of five parts:

1. Hardware (Equipment that processes the data to create information)

2. Software (Step-by-step instructions that convert data into information)

3. Data (unprocessed facts)

4. Procedures (Rules or guidelines to follow when using Hardware and software

5. People (End user who is the most important part of IS)

I'm actually not familiar with Access, but I'll try to help. Usually the primary key will physically order the rows in a database table. In SQL-query you can use "order by" clause. The default order is usually ascending. You can also add "asc" or "desc" after the column name.

Please do notice, primary keys are not for ordering rows. You should really let the database decide how to save the rows. You should always order the rows in your query (if needed), not modify or trust the physical order!

select col1

from foo

order by col2

select col1

from foo

order by col2 desc, col3 asc

top level

120

To create a drop-down field on a table in Access, you can do this:

1. Open the table in design view.

2. If you haven't already, create the field and specify its characteristics on the 'General' tab(i.e. data type, field size, etc...). The tab is in the lower-half of the screen.

3. Select the field you wish to make as a drop-down.

4. There is another tab next to 'General' named 'Lookup'. Click on that.

5. Set the following Field Properties as follows:

a. Display Control: Combo Box

b. Row Source Type: Value List

c. Row Source: Here you can enter a list of acceptable values, separated by a semicolon. Example: if you want the user to specify from 3 choices (such as A, B or C), you'd enter: A;B;C.

d. Limit To List: Yes - recommended if you don't want the user to enter values other than what you've defined above.

As a minimum, this info may be enough to get your started. Note that this info comes from Office 2007 and your version may be different, thus some options may not be available.

Hope this is enough to start you off. Keep in mind, there is always more than one way to do what it is you ask. Good luck!

warehouse- what you say when lost

Features of DBMS A typical DBMS has the following features: • Provides a way to structure data as records, tables, or objects

• Accepts data input from operators and stores that data for later retrieval

• Provides query languages for searching, sorting, reporting, and other "decision support" activities that help users correlate and make sense of collected data

• Provides multiuser access to data, along with security features that prevent some users from viewing and/or changing certain types of information

• Provides data integrity features that prevent more than one user from accessing and changing the same information simultaneously

• Provides a data dictionary (metadata) that describes the structure of the database, related files, and record information

Some limitations of computerized accounting systems are the cost, security, and susceptibility to human error. It should be kept in mind that just because something is entered into a computer does not mean that it is error-free.

check

ntdis.dit

The question is a bit short but I cured a locking problem with the following if it helps?

-- MESSAGE "Data" OR "Information" "is out of date" on some APP screens.

--

-- Identify which table is affected. In this case we know that

-- ops are stored in table WTL. We now need a session_id and serial number

-- so we can invoke the kill command against this rogue process.

--

-- sqlplus system/password@schemaname

select object_id from dba_objects where object_name ='WTL';

--3738

--3820

--3930

--3335

--

-- The following was run against 3738, 3820 and 3930 but nothing was returned

-- However when run against 3335 returned a session_id of 71

select * from v$locked_object where object_id=3335;

-- All we need now is the serial number so we can kill the rogue process.

--

select sid, serial#, command, taddr from v$session where sid=71;

--

-- This returned us a serial number 16711

--

-- All the above can be combined as below:

--

select sid, serial#, command, taddr

from v$session

where sid=(select SESSION_ID

from v$locked_object

where object_id in (select object_id

from dba_objects

where object_name='WTL'))

-- If we are sure this is the rogue lock then kill it.

alter system kill session '71,16711';

-- If it refuses to die use

alter system kill session '71,16711' IMMEDIATE ;

--

-- NOTE: Your sid and serial number will be different from this example!

-- NOTE: Closing the APP window and waiting 10 minutes can (sometimes) also cure the fault.

Ctrl Z.

DOS

Classes.

1. Primery Key.

Alternatively referred to as a negative indent, a hanging indent is an indent that indents all text except the first line. useful for paragraphs

automatic teller machine

yes

A file system is necessary for a computer to work with files; however, a file system is not a physical object, and is pretty useless without a computer to use it on.

A byte is the smallest unit of addressable storage. Although a bit is smaller than a byte, a single bit cannot be addressed directly; we always deal with groups of bits and a byte is the smallest group of bits that can be physically addressed. However, once we have addressed a byte, we can then examine the individual bits within it using the bitwise logic operators (AND, OR, NOT and XOR).

On most systems a byte is exactly 8 bits in length. The reason for this is simply that we can represent any 8-bit value using a convenient two-digit hexadecimal notation, where each hex digit represents exactly 4-bits (often called a nybble because it is half-a-byte). Thus an 8-bit byte can be represented by any hexadecimal value in the range 0x00 to 0xff (or 0 to 255 decimal).

(Some systems use odd-size bytes, such as a 9-bit byte. For this we typically use 3-digit octal notation because an octal digit represents exactly 3 bits. Such systems are rare, but we sometimes come across other odd-sized bytes, especially in older data transfer systems such as dot-matrix printers which utilised a 7-bit byte. However, in modern architecture, we can safely say that a byte is always at least 8 bits long.)

Not all programming languages utilise a byte data type as such. C, for instance, doesn't have a built in byte data type but it does have a char data type which is always 1 byte in length. There's no real reason why there isn't a byte data type in C, but when all data types are measured in terms of bytes it was probably deemed unnecessary to say that a byte is 1 byte in length. Although a char is typically used to encode a single character from a character set (and has built in overloads specific to that purpose), the encoding is no less numeric than a byte would be, so there was no real need for a separate byte data type.

Although a single byte can represent any decimal value in the range 0 to 255, it is more correct to say that a single byte can represent any one of 256 unique abstractions. Whether it is a single character from a character set, an unsigned value in the range 0 to 256, or a signed value in the range -128 to +127, these are merely abstractions. How abstractions are interpreted is entirely down to the programmer and/or the programming language.

Manual filing is the process of actually handling a physical piece of data. In the days before computers, a person made a folder of data and kept it in a filing cabinet, alphabetized or according to category.

When the early computers came along, people then converted the data to a punch card system that was readable to the computer. These looked like envelopes but were made of a light cardboard and were loaded into a punch card reader in a stack. The reader then entered the data into the computer, the cards were removed, and and another pile put into the machine.

Aren't you glad that progress has been made in making computers work today?