Visual Basic. NET (VB.NET)

Visual Basic. NET (VB.NET) is a language of object-oriented programming can consider changes implemented on the Visual Basic. NET framework.

As with all programming languages. NET-based, programs written in VB. NET Framework require the. NET to run.

Features (Visual Basic 6.0 does not own):

• Heritage
• Polymorphism
• Encapsulation

The Visual Studio 2008 to work against 3. NET different frameworks:

. NET Framework 2.0

. NET Framework 3.0

. NET Framework 3.5

It is also very easy to use with hardware development.

In addition, integrating the ASP.NET AJAX framework for developing AJAX.

Components. NET Framework:

• CLR (Common Language Runtime)
• Class library. NET Framework
• ADO.NET: Data and XML
• ASP.NET: Forms and Web services
• User Interface

  

Visual Basic Type	Structure common language runtime	Nominal storage allocation	Range of values
Boolean	Boolean	Depending on the deployment platform	True or False
Byte	Byte	1 byte	0 to 255 (unsigned)
Char (single character)	Char	2 bytes	0 to 65535 (unsigned)
Date	DateTime	8 bytes	0:00:00 (midnight) on January 1, 0001 at 11:59:59 pm on December 31, 9999.
Decimal	Decimal	16 bytes	0 to + / -79,228,162,514,264,337,593,543,950,335 (+ / -7.9 ... E +28) † with no decimal point, 0 to + / -7.9228162514264337593543950335 with 28 places to the right of the decimal; nonzero numbers smaller + / -0.0000000000000000000000000001 (+ /-1E-28) †
Double (double precision floating point)	Double	8 bytes	E -1.79769313486231570 -4.94065645841246544 +308 to E-324 † for negative values; 4.94065645841246544 E-324-1.79769313486231570 E +308 †for positive values
Integer	Int32	4 bytes	-2,147,483,648 To 2,147,483,647 (signed)
Long (long integer)	Int64	8 bytes	-9,223,372,036,854,775,808 To 9,223,372,036,854,775,807 (9.2 ... E +18 †) (signed)
Object	Object (class)	4 bytes in 32-bit platform 8 bytes on 64-bit platform	Any type can be stored in a variable of type Object
SByte	SByte	1 byte	-128 To 127 (signed)
Short (short integer)	Int16	2 bytes	-32,768 To 32,767 (signed)
Single (single-precision floating point)	Single	4 bytes	-1.401298 -3.4028235 E +38 to E-45 † for negative values; 1.401298 E-45 to 3.4028235 E +38 † for positive values
String (variable length)	String (class)	Depending on the deployment platform	0 to 2,000 million Unicode characters approx.
UInteger	UInt32	4 bytes	0 to 4,294,967,295 (unsigned)
ULong	UInt64	8 bytes	0 to 18,446,744,073,709,551,615 (1.8 ... E +19 †) (unsigned)
User-Defined (structure)	(Inherited deValueType)	Depending on the deployment platform	Each member of the structure has a range of values ​​determined by its data type and is independent of the range of values ​​for the other members.
UShort	UInt16	2 bytes	0 to 65,535 (unsigned)

• 
  

• Summary of Visual Basic.NET

• Major changes to take advantage of. NET famework
• Streamlined and consistent language.
• Characteristics "inherited" have finally been removed.
• Visual Basic.NET code can be reused.
• Support for migration.  

Visual FoxPro

Visual FoxPro is a programming language, object oriented and procedural, Manager System Databases or Database Management System (DBMS). 

Features

Visual FoxPro offers developers a set of tools for building database applications for desktop, client / server, tablet PC or the Web.

Features include:

• Very fast and powerful capabilities for data management and remote native.
• Flexibility to create all types of database solutions.
• Language Object Oriented Programming.
• Using SQL Statements in native form.
• Powerful order management, full control cursors and relational structures.
• Your own database manager built. However, it also can connect to database servers such as Oracle, Microsoft SQL Server or MySQL.
• It has a reporting engine renovated and very flexible for more robust solutions.

VISUAL FOX PRO COMMANDS

To change the working directory:

SET TO DEFAULT directory path.

Example: SET DEFAULT TO c: / ​​system / billing

Clean the main screen of Visual Fox Pro:

CLEAR.

Show files in the directory:

DIR

Examples: DIR

DIR *. TXT

DIR C: / My Documents / BILLING

To turn off the connection or talk of VFP:

SET TALK OFF

This is done because when you delete, create indexes, etc.. VFP on the screen will show the results, which is why a program should include.

To change the date format:

TO SET DATE format

TO SET DATE DMY

SET DATE TO MDY

SET DATE TO BRITISH

To exit the VFP:

QUIT

To cancel the execution of a program:

CANCEL

To open a database:

OPEN DATABASE Name of database.

Example: OPEN DATABASE billing

To Close a Database:

CLOSE DATABASES

To open a table:

USE name of the table.

Example: USE billing

To open a database:

OPEN DATABASE Name of database.

Example: OPEN DATABASE billing

TAG USE ​​ORDER billing product

(Selecting the index to open the table to not use set order)

To close a table:

USE

To close all tables:

CLOSE TABLES

Add a blank record:

APPEND BLANK

Deleting records:

DELETE

Example: DELETE (DELETE CURRENT)

DELETE ALL (ALL CLEAR)

DEPT FOR DELETE = "0132" (CLEAR THAT ONLY THE DEPT.)

DELETE NEXT 5 (DELETE THE FOLLOWING 5 AFTER THE ACTUAL)

Retrieve records marked as deleted:

RECALL

Example: RECALL (RECOVER ACTUAL)

RECALL ALL (COLLECT ALL)

RECALL FOR DEPT = "0132" (RECALL THAT ONLY THE DEPT.)

RECALL NEXT 5 (RECOVER AFTER CURRENT FOLLOWING 5)

Remove deleted records as marked:

PACK

Permanently delete all the records (and can not be recovered):

ZAP

To go to the last record in the table:

GO TOP

To go to the last record in the table:

GO BOTTOM

To go to a specific registry:

GO registry number

Example: GO 10

To skip to register:

SKIP

Example: SKIP 1 (Skip forward 1 record)

SKIP -1 (Skip back 1 record)

To open one or more tables (Workspaces)

SELECT

SELECT Workspace (Number or Letter)

USE TABLE

Example: SELECT A

Billing USE

Example: SELECT B

Customer USE

           

To change the Work Area:

SELECT

SELECT Workspace

Example: SELECT A

Example: SELECT Customers

To establish the rate of job:

ORDER TO SET Index Name

Example: SET ORDER TO name

Billing USE

Example: To not use any indexes of Work:

ORDER TO SET

To set filters condition:

SET FILTER TO Filter Condition

Examples: SET FILTER TO salary> 1000

                              SET FILTER TO salary> = 1000. and. salary <= 3000

FILTER TO SET salary = 1000. or. salary = 2000

SET FILTER TO dept <> "0004." and. (salary = 1000. or. salary = 2000)

First are evaluated are in parentheses and then the outside.

To find information without active index:

Search Condition LOCATE FOR

Examples: LOCATE FOR numero_empleado = "09499"

To find information with an active index:

SEEK to search for information (variable, number or text string)

Examples: SEEK "09499"

SEEK num_empleado

SEEK 1235

To this must be an active index with ORDER TO SET or opening the table with the TAG ORDER option index name.

Consider the information:

BROWSE

Examples: USE employee

BROWSE

                               0

BROWSE FIELDS key, name, salary (this was omitted dept)

0

BROWSE FOR dept = "0003" (only this dept)

Here you can use a mixture of all.

Display List Logs:

LIST ^[Campos] (optional)

Examples: LIST (List all fields on the screen)

LIST key, name, salary (List only those fields)

LIST FOR dept = "0012" (list only the dept)

OFF LIST (List without registration number)

Here you can use a mixture of all, the only downside is that if too many records, and deployed all, and through the first records up and no longer be seen.

List records to the printer:

Same as above except that at the end of the instruction is added TO PRINT

Examples: LIST key, name, salary TO PRINT

Display Screen records:

For this only replaces the instruction by DISPLAY LIST

This has the advantage that when you call the display of records, the VFP pauses so that you can read and then continue.    

Modify the structure of a table:

MODIFY STRUC

Printer Display Screen or the structure of a table:

DISPLAY STRUCT

O

DISPLAY STRUCT TO PRINT