A function that is built into an application and can be accessed by end-users.
A function is similar to a normal procedure but the main purpose of the function is to accept a certain input from the user and return a value which is passed on to the main program to finish the execution. There are two types of functions, the built-in functions (or internal functions) and the functions created by the programmers. he general format of a function is
FunctionName (arguments) The arguments are values that are passed on to the function.
Built -in function are classified under following categories * Math Functions * Conversion Functions * String Functions * Date and Time Functions * Array Functions * Misc. Functions
Math Functions * Abs(vNumber) - Returns the absolute value of a specified number * Atn(vNumber) - Returns the arctangent of a specified number * Cos(vNumber) - Returns the cosine of a specified number (angle) * Exp(vPower) - Returns e raised to a power * Hex(vNumber) - Returns the hexadecimal value of a specified number * Int(vNumber) - Returns the integer part of a specified number * Fix(vNumber) - Returns the integer part of a specified number * Log(vNumber) - Returns the natural logarithm of a specified number * Oct(vNumber) - Returns the octal value of a specified number * Rnd() - Returns a random number less than 1 but greater or equal to 0 * Sgn(vNumber) - Returns an integer that indicates the sign of a specified number * Sin(vNumber) - Returns the sine of a specified number (angle) * Sqr(vNumber) - Returns the square root of a specified number * Tan(vNumber) - Returns the tangent of a specified number (angle) Conversion Functions * CBool(vVariant) - Converts an expression to a variant of subtype Boolean * CByte(vVariant) - Converts an expression to a variant of subtype Byte * CCur(vVariant) - Converts an expression to a variant of subtype Currency * CDate(vVariant) - Converts a valid date and time expression to the variant of subtype Date * CDbl(vVariant) - Converts an expression to a variant of subtype Double * CInt(vVariant) - Converts an expression to a variant of subtype Integer * CLng(vVariant) - Converts an expression to a variant of subtype Long * CSng(vVariant) - Converts an expression to a variant of subtype Single * CStr(vVariant) - Converts an expression to a variant of subtype String
String Functions * InStr(sString, sSubString) - Returns the position of the first occurrence of one string within another. The search begins at the first character of the string * InStrRev(sString, sSubString) - Returns the position of the first occurrence of one string within another. The search begins at the last character of the string * LCase(sString) - Converts a specified string to lowercase * Left(sString, iLen) - Returns a specified number of characters from the left side of a string * Len(sString) - Returns the number of characters in a string * LTrim(sString) - Removes spaces on the left side of a string * RTrim(sString) - Removes spaces on the right side of a string * Trim(sString) - Removes spaces on both the left and the right side of a string * Mid(sString, iStart, iLen) - Returns a specified number of characters from a string * Replace(sString, sOld, sNew) - Replaces a specified part of a string with another string a specified number of times * Right(sString) - Returns a specified number of characters from the right side of a string * Space(iLen) - Returns a string that consists of a specified number of spaces * StrComp(sString1, sString2) - Compares two strings and returns a value that represents the result of the comparison * String(iLen, sChar, iLen) - Returns a string that contains a repeating character of a specified length * StrReverse(sString) - Reverses a string * UCase(sString) - Converts a specified string to uppercase * Asc(sString) - Converts the first letter in a string to ANSI code * Chr(iInteger) - Converts the specified ANSI code to a character Date and Time Functions * CDate(vVariant) - Converts a valid date and time expression to the variant of subtype Date * Date() - Returns the current system date * DateAdd(sType, iInterval, tDate) - Returns a date to which a specified time interval has been added * DateDiff(tDate1, tDate2) - Returns the number of intervals between two dates * DatePart(sType, tDate) - Returns the specified part of a given date * DateSerial(iYear, iMonth, iDate) - Returns the date for a specified year, month, and day * DateValue(vVariant) - Returns a date * Day(tDate) - Returns a number that represents the day of the month (between 1 and 31, inclusive) * FormatDateTime(tDate, iType) - Returns an expression formatted as a date or time * Hour(tDate) - Returns a number that represents the hour of the day (between 0 and 23, inclusive) * IsDate(vVariant) - Returns a Boolean value that indicates if the evaluated expression can be converted to a date * Minute(tDate) - Returns a number that represents the minute of the hour (between 0 and 59, inclusive) * Month(tDate) - Returns a number that represents the month of the year (between 1 and 12, inclusive) * MonthName(iMonth) - Returns the name of a specified month * Now() - Returns the current system date and time * Second(tDate0 - Returns a number that represents the second of the minute (between 0 and 59, inclusive) * Time() - Returns the current system time * Timer() - Returns the number of seconds since 12:00 AM * TimeSerial(iHour, iMinute, iSecond) - Returns the time for a specific hour, minute, and second * TimeValue(tDate) Returns a time * Weekday(tDate) - Returns a number that represents the day of the week (between 1 and 7, inclusive) * WeekdayName(iWeekDay) - Returns the weekday name of a specified day of the week * Year(tDate) - Returns a number that represents the year
Array Functions * Array(vArg1, vArg2, ...) - Returns a variant containing an array * IsArray(vVariant) - Returns a Boolean value that indicates whether a specified variable is an array * Join(aArray) - Returns a string that consists of a number of substrings in an array * LBound(aArray) - Returns the smallest subscript for the indicated dimension of an array * Split(sString, sDelimiter) - Returns a zero-based, one-dimensional array that contains a specified number of substrings * UBound(aArray) - Returns the largest subscript for the indicated dimension of an array
Misc. Functions * IsArray(variable) - Returns True if the specified variable is an array * IsDate(variable) - Returns True if the specified variable can be converted to a date * IsEmpty(variable) - Returns True if the specified variable is Empty * IsNull(variable) - Returns True is the specified variable is Null * IsNumeric(variable) - Returns True if the specified variable can be converted to a number * IsObject(variable) - Returns True if the specified variable is an object * TypeName(variable) - Returns the type name of the specified variable * VarType(vVariant) - Returns the type code of the specified variable
1 Explain architecture of Distributed Database systems? Also, explain the reasons for building distributed database systems?
what are the disadvantages of centralized database system
functions of DBA in DBMS
Replicated Allocation ie copies of one or more database fragments are stored at several sites.
the architecture of dbms contains three levels 1/ external level:different users views of the database,shows relevant data for a particular user. 2/conceptual level:global view pf the database;describes what data is stored and its relationships. 3/internal level:physical representation of the database on the computer, Describes how the data is stored in the database.
a representation of DBMS design. It helps to design, develop, implement, and maintain the database management system. A DBMS architecture allows dividing the database system into individual components that can be independently modified, changed, replaced, and
Classification of Advanced OS is done as below:Architecture driven systems, and Application driven system. 1. Architecture driven: * Network OS * Distributed OS * Multiprocessor OS 2. Application driven: * Database OS * Real Time OS * Multimedia OS
explain DRAM architecture with block diagram?
In Heuristic-based Optimization, the query execution is refined based on heuristic rules for reordering the individual operations.
chandranana explain the characteristic of database?
the client is on the first tier. The database server and web application server reside on the same server machine, which is the second tier. This second tier serves the data and executes the business logic for the web application
explain how database makes paying for products on the internet possible?