Searchable Databases

[Token]

Databases and how to search through them

The first thing that you want to do is create your database, so we''ll set up a record. Example we'll use is an adress book

code:

type phonerecord :     record         first : string         last: string         home : string (8)         cell : string (8)         fax : string (11)     end record var entry : array 1 .. 50 of phonerecord

okay now we're all set to gather the information. so we will assume that we already have a file set up with a couple of entries in this format
first name, last name, home number, cell number, fax number.

code:

Joe, Smith, 555-1234, 555-4321,  44-171-343433

Okay so now we'll input all of this information into our reccord through a loop.

code:

var stream, counter : int := 0 %%%%% :=0 is to error proof so it dosent crash at += var data : string open : stream, "archive.txt", get loop     counter += 1     exit when eof (stream)     get : stream, data     entry (counter).first := data     get : stream, data     entry (counter).last := data     get : stream, data     entry (counter).home := data     get : stream, data     entry (counter).cell := data     get : stream, data     entry (counter).fax := data end loop close : stream

Okay, so our system is now created and the data is entered. so now what we have to do is find the name of who their searching for. we'll make this search by last name only.

code:

var search : string put "Enter the persons last name: " .. get search

Alright, so now we have our search, in this case we're searching for Smith...so we run the variable 'search' through the entire record and compare it to the other last names, if its the same then we display it on the screen

code:

for i : 1 .. counter     if entry (i).last = search then         put "\nFirst name: ", entry (i).first         put "Last  name: ", entry (i).last         put "Home: ", entry (i).home         put "Cell: ", entry (i).cell         put "Fax: ", entry (i).fax     end if end for

Tadum! and then it pops up with the results that matched, you can change it to search for first name or number or somthing just by changing where it says

code:

if entry (i).last = search then

so there you have it, a searchable database, simple and easy to add and modify.

all that code combined is below, along with what would be in the text file, 'archive.txt'

code:

%%% type phonerecord :     record         first : string         last : string         home : string         cell : string         fax : string     end record var entry : array 1 .. 50 of phonerecord %%% var stream, counter : int := 0 %%%%% :=0 is to error proof so it dosent crash at += var data : string open : stream, "archive.txt", get loop     exit when eof (stream)     counter += 1     get : stream, data     entry (counter).first := data     get : stream, data     entry (counter).last := data     get : stream, data     entry (counter).home := data     get : stream, data     entry (counter).cell := data     get : stream, data     entry (counter).fax := data end loop close : stream %%% var search : string put "Enter the persons last name: " .. get search for i : 1 .. counter     if entry (i).last = search then         put "\nFirst name: ", entry (i).first         put "Last  name: ", entry (i).last         put "Home: ", entry (i).home         put "Cell: ", entry (i).cell         put "Fax: ", entry (i).fax     end if end for

Quote:

Joe Smith 555-1234 555-4321 44-171-343433

if you have any questions or comments please let me know.

[jamonathin]

Good tutorial. Our teacher was actually trying to teach us that this year. Even though that was the only thing, and he did it some wierd ass complete different way . . . nvm, lol, but yeah good work on that tut.

And im not too sure why you did this

code:

put "\nFirst name: ", entry (i).first

Im pretty sure that for C++, but anyways, good job.

+ 10 Bits

Next to work on is the option of playing around with that data. Such as (D)elete or (W)rite and so on.

[GlobeTrotter]

You could also do a binary search for this problem. It would require sorting the array of records, but the actual searching would be much quicker. FOr example, in an array of 100 names, you way would run through 100 times. Binary Search would run through 7.

[Token]

Hey, well i used put "\nFirst name: ", entry (i).first to display the name, the \n is to set it down a line without just doing a blank put statement (put ""). and could you please explain to me more about this binary thing?

ps. thanks for the bits jamonathin

[GlobeTrotter]

I'll describe a case which used binary search.
Say I ask you to guess a number between 1 and 100. If after each guess, I tell you whether the guess is higher or lower, you are guaranteed to get it within 7 guesses if you make the right guesses. For example, if you picked the number 13: First you'd guess 50, then 25, then 13. In three guesses.

Basically, you do the same thing with a sorted array of records. You go the midway point of the left and right vals, and check if its higher, lower, or equal. If different, you reset the left and right vals.

[md]

You have to make sure that whatever your searching is sorted first, generally if your doing a binary search you quicksort first.

[Token]

Hmm inturesting, this would work better for a larger database tho, with phone numbers, really you would only have a maximum of 50-75 contacts, so time isnt really of the essence, but if you were sorting information for say the school's contact information, you would want to do it in a binary sort of fashion. thanks for that info guys and i might add onto the tut. and put it in there.

[Weelkid_29]

code:

type seat :     record         lastname : string         firstname : string         address : string         phonenum : string     end record var seat_record : array 1.. 10 of seat for i : 1 .. 10     put "enter ur last name " ..     get seat_record (i).lastname     put "enter ur first name " ..     get seat_record (i).firstname     put "enter ur address "     get seat_record (i).address : *     put "enter ur phone number "     get seat_record (i).phonenum end for var lastname : string put "Enter the last name" get lastname var flag : int := 0 for a : 1 .. 10     if lastname = seat_record (a).lastname then         flag := 1         put "record found"         put seat_record (a).lastname         put seat_record (a).firstname         put seat_record (a).address         put seat_record (a).phonenum     else     end if end for if flag = 0 then     put "record not found" end if

enter all the info for the record
then enter the last name for the info u want