Today's topic: DATABASE
What is database?
-Organized collection of information
-a repository for information organized in such a way that a computer program can quickly select or retrieve desired pieces of data
Examples:
-code in matric card to store all details about the student (stored in 1 database)
-borrowing books from library (stored how much books you borrowed)
-telephone books
-collection of music
-list of students
Analogy
Database (a rack)---> you can put stuff in & out (like a folder)
*there are many ways to organize a 'cabinet'
-classify files into their types
2 Types of database(how we design the database?): Flat vs relational
-the way you design database will determine how fast the database runs-->& this leads to normalization
1-Microsoft excel-Flat (everything is stored in 1 table)
-repeating information
-slow to retrieve information
-difficult to re-organize info
-increase risk of typos
-no transactions
2-Microsoft access -Relational (break down information into different types-student's info, course info, mahallah info)-each data in each tables should be related to each other (eg: same student ID)
-Advantages
- organized database
-sorting using tables-->
-summarizing it using reports
-extracting in
-breaks part into different tables
-relates/connects tables with unique key (different matric numbers)
-prevents duplicate information
-it's efficient and less prone to error
-optimizes the performance-retrieve from 1 specific information-->easy to search-needs less time to retrive information
Normalization
-the process of splitting data across multiple tables to improve overall performance, integrity(repeating) & longevity(the way how we retrieve-take less time)
-split out data into a particular table-->we need relationship to split the tables
Why normalize
-no need to repeat information(which will takes up unnecessary space)
-data grow exponentially(rapidly)-will affects the storage
-To avoid slow performance
-To avoid inconsistency-which can avoid searches
How to normalize?
-By splitting the data
Objects in database
-it refers to individual components that comprise database
4 basic objects: -->complete database
-tables-to store
-forms-to design the interphase -how you want to design the data
-queries-to retrieve informations from table
-reports
-macros & modules (visual basic)
What is the heart of the database?
-The tables
-The most important object in database
Why?-->
- we cannot key in data without tables (we cannot report without tables)
What is table?
-a collection of information organized into:
- Fields( columns in table)
- Records (the rows in the tables)
- Data values (the actual information itself)
- Data type(auto number, text,number, currency, date/time, yes/no, attachment, hyperlink-via email, memo, lookups)
Space:
Limit 2GB-the space needed for system objects-should avoid repeating information
Numbers of objects in database=32,768
Characters per object name =64
Number of concurrent users=255
Exercise
-view
-insert field names
-specify the data type
-i can edit the caption...
*learning database will helps in understanding programming better... :)
Extra note
Khalasss~~
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