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Data flow diagram Data flow diagram example. [1] A data flow diagram ( DFD ) is a graphical representation of the "flow" of data through an information system , modelling its process aspects. A DFD is often used as a preliminary step to create an overview of the system, which can later be elaborated. [2] DFDs can also be used for the visualization of data processing (structured design). A DFD shows what kind of information will be input to and output from the system, where the data will come from and go to, and where the data will be stored. It does not show information about the timing of process or information about whether processes will operate in sequence or in parallel (which is shown on a flowchart ). Contents 1 History 2 Theory 2.1 Physical DFD 3 See also 4 References 5 Further reading 6 External links History Larry Constantine , the original developer of structured design, [3] based on Martin and Estrin&#
A Simple Example CREATE DATABASE mydb ; USE mydb ; CREATE TABLE mytable ( id INT PRIMARY KEY , name VARCHAR ( 20 ) ); INSERT INTO mytable VALUES ( 1 , 'Will' ); INSERT INTO mytable VALUES ( 2 , 'Marry' ); INSERT INTO mytable VALUES ( 3 , 'Dean' ); SELECT id , name FROM mytable WHERE id = 1 ; UPDATE mytable SET name = 'Willy' WHERE id = 1 ; SELECT id , name FROM mytable ; DELETE FROM mytable WHERE id = 1 ; SELECT id , name FROM mytable ; DROP DATABASE mydb ; SELECT count ( 1 ) from mytable ; gives the number of records in the table
An Introductory SQL Tutorial: How to Write Simple Queries Written by Rachel Sprung | @ SHARE Tweet 99 in Share Ever heard of the computer language called SQL? You may have heard about it in the context of data analysis, but never really thought it would apply to you as a marketer. Or, you may have thought to yourself, "That's for the really advanced data users. I could never do that." Well, you couldn't be more wrong! The most successful marketers are data-driven, and one of the most important parts of being data-driven is being able to collect data from databases quickly. SQL happens to be one of the best and most popular tools out there for doing just that. SQL stands for Structured Query Language, and it's used when companies have a ton of data that they want to manipulate in an easy and quick way. If your company already stores data in a database, you may need to learn SQL to access the data. But not to worry -- you
What is the difference between data and information? Most people believe that the terms "data" and "information" are interchangeable and mean the same thing. However, there is a distinct difference between the two words . Data can be any character , text, words, number, pictures , sound , or video and, if not put into context, means little or nothing to a human. However, information is useful and usually formatted in a manner that allows it to be understood by a human. Computers typically read data, but it is not necessarily something that a computer actually understands. Through the use of formulas, programming scripts, or software applications, a computer can turn data into information that a human can understand. Below is an example of the same data and information and how they differ.