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Lesson 5Data Types and Databases
Objective Coerce scripting data types to match database types.
When a database is designed the columns are defined with a specific data type . As an example, names and addresses would be character strings, quantities would probably be integers, and other values such as temperature could be floating point data types.
The data types used in script might not match that used in the database. VBScript has only one data type, called the variant type. The variant stores all the data types and are referred to as subtypes. Additionally, parameters, or name/value pairs, passed in HTTP query strings are just that, strings. Therefore you should check data types before storing them in the database or using them in expressions such as arithmetic or comparisons. If this isn't done, errors or unpredictable results could occur.
Most, if not all, scripting languages have some level of data conversion capability. We'll look at the VBScript conversion functions in this lesson. The following table lists the data conversion functions available in VBScript.
  1. data type: A variable or field attribute that specifies the kind of data it can hold.
  2. floating point data type: A single precision number containing a sign bit and a 23-bit mantissa.
  3. variant: The data type for all variables that are not explicitly declared as a specific type.
  4. subtype: The different data types represented by the variant type.

Function Description Syntax
Asc Returns the ANSI character code for first character in a string Asc(string)
CBool Returns an expression converted to a Boolean CBool(expression)
CByte Returns an expression converted to a Byte CByte(expression)
CCur Returns an expression converted to subtype Currency CCur(expression)
CDate Returns an expression converted to a Date CDate(expression)
CDbl Returns an expression converted to a Double CDbl(expression)
Chr Returns the character associated with the specified character code Chr(code)
CInt Returns an expression converted to an integer Cint(expression)
CLng Returns an expression converted to a Long Clong(expression)
CSng Returns an expression converted to a Single CSng(expression)
CStr Returns an expression converted to a string CStr(expression)
Hex Returns a string representing the hexadecimal value of a number Hex(number)
Oct Returns a string representing the octal value of a number Oct(number)

The following script code checks to see if the variable type is an integer. If it isn't, the value is converted to an integer and stored in a new variable.
if VarType(oldvariable) <> 2 then
 newvariable = CInt(oldvariable)
end if

The VBScript VarType function returns the type stored in the variable. It returns a 2 for the integer type.
In the next lesson, you will learn how to access data without using Design-Time Controls.

Data Conversion Functions

Click the Exercise link below to test what you have learned about data types.
Data Conversion Functions