Learning objectives: To learn about data flow diagrams (DFDs) and the symbols used in them, to understand a context diagram and its decomposition, to understand the standard symbols used in flow charts. | Documentation techniques and databases Learning objectives To learn about data flow diagrams (DFDs) and the symbols used in them. To understand a context diagram and its decomposition. To understand the standard symbols used in flow charts. To describe and construct different types of flow charts. To understand the advantages of flow charts over written descriptions. To be able to compare and contrast DFDs and flow charts. To understand decision tables and their relevance to programming. To learn about the construction of E-R diagrams as a basis for databases. key terms attribute binary notation bit byte context diagram data dictionary data flow data flow diagram data model data store data structure data warehouse database database management system decision table decomposition of a data flow diagram key terms (cont.) documentation entity E-R diagram flow charts flow line foreign key lead time primary key relational database model relationship schema secondary key subschema Data flow diagrams Graphically describe the flow of data within an organisation Composed of four basic elements represented by standard symbols: Basic data flow diagram Data flow diagram for customer delivery dates Context diagrams Show major data flows into and out of a system Describe each subsystem as a process showing interrelationship of those subsystems and their relationship to main system Context diagrams Depict logical flow of data in summary form The starting point for studying any system Depict the system at its highest level Referred to as level zero data flow diagrams Flow charts Document physical flows determined after logical data flows have been documented using data flow diagrams Flow chart symbols Advantages and disadvantages of flow charts Advantages: Enable any system to be represented in easily understandable manner Overall picture of system easily seen Highlight relationship among different parts of the system Disadvantages: Creation can be time-consuming Numerous symbols . | Documentation techniques and databases Learning objectives To learn about data flow diagrams (DFDs) and the symbols used in them. To understand a context diagram and its decomposition. To understand the standard symbols used in flow charts. To describe and construct different types of flow charts. To understand the advantages of flow charts over written descriptions. To be able to compare and contrast DFDs and flow charts. To understand decision tables and their relevance to programming. To learn about the construction of E-R diagrams as a basis for databases. key terms attribute binary notation bit byte context diagram data dictionary data flow data flow diagram data model data store data structure data warehouse database database management system decision table decomposition of a data flow diagram key terms (cont.) documentation entity E-R diagram flow charts flow line foreign key lead time primary key relational database model relationship schema secondary key subschema Data flow
