Data base
- 1. Attributes are properties of interest that further describe the entity TYPES OF ATTRIBUTES COMPOSITE VS SIMPLE ATTRIBUTES SINGLE VALUE VS MULTI-VALUED ATTRIBUTES STORED VS DERIVED ATTRIBUTES NULL VALUES COMPLEX ATTRIBUTES
- 2. COMPOSITE VS SIMPLE ATTRIBUTES Composite attributes can be divided into smaller sub-parts to represent some more basic attributes Eg. Name of a person – composite(first name, second name etc.) Simple attributes can not be sub divided Eg. Height of a person
- 3. SINGLE VALUE VS MULTI-VALUED ATTRIBUTES An attribute with a single value for an entity is single –valued as opposed to those with multiple values Eg.Height of a person-single valued Qualification of a person- multi valued attributes
- 4. Null values Absence of a data item is represented by a special value called null value
- 5. Complex attributes The composite and multi–valued attributes may be grouped to constitute complex attributes
- 6. Any attribute which contains unique values for identifying the entity instance is known as identifier Eg.roll no of a student
- 7. It refers to a set of techniques that are used to design a data base. These techniques use certain concepts which are crucial to the creation of structure and development of the design
- 8. The relational data model represents the database as collection of relations ,which resembles a table of values row – tuple( an ordered set of values) column header- attribute table –relation data type describing the types of values- domain domain is a set of indivisible values
- 9. ACCOUNTING SYSTEM USING DATABASE MANAGEMENT SYSTEM Query- a request for information from a data base SQL-Structured Query Language SQL is used to communicate with a data base
- 10. Simple query A query which does not involve use of any query function to produce a summary of data TYPES OF QUERIES
- 11. Parametre query A parameter query prompts the user to enter parameters, or criteria through an input box for selecting a set of records TYPES OF QUERIES
- 12. Summary query A summary query is used to extract aggregate of data items for a group of records rather than a detailed set of records TYPES OF QUERIES