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Flashcards by diksha.kumari98, updated more than 1 year ago
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Created by diksha.kumari98
almost 12 years ago
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| Question | Answer |
| 1.1 Objectives | understand the data organization; define the term ‘data structure’; know the classifications of data structures, i.e., linear and non-linear ; understand the basic operations of linear and non-linear data structures; explain the memory representation of all types of data structures and tell that how to implement the all kinds of data structures. |
| 1.2 DATA | Data are simply values or set of values |
| DATA ITEM | A data item is either the value of a variable or a constant. For example, a data item is a row in a database table, which is described by a data type. |
| ELEMENTARY ITEMS | A data item that does not have subordinate data items is called an elementary item. |
| GROUP ITEMS | A data item that is composed of one or more subordinate data items is called a group item |
| RECORDS | A record can be either an elementary item or a group item. For example, an employee’s name may be divided into three sub items – first name, middle name and last name – but the social_security_number would normally be treated as a single item. |
| FEILDS | a field is a single elementary unit of information representing an attributes of an entity |
| RECORDS | a record is the collection of field values of a given entity |
| FILE | file is the collection of records of the entities in given entity set. |
| PRIMARY KEY | Each record in a file may contain many field items, but the value in a certain field may uniquely determine the record in the file. Such a field K is called a Primary Key |
| FIXED LENGTH RECORD | In fixed-length records, all the records contain the same data items with the same amount of space assigned to each data items with the same amount of space assigned to each data item. |
| VARIABLE LENGTH RECORD | In variable-length records, file records may contain different lengths. |
| To learn about these data structures, we have to follow these three steps: | 1. Logical or mathematical description of the structure. 2. Implementation of the structure on a computer. 3. Quantitative analysis of the structure, which includes determining the amount of memory needed to store the structure and the time required to process the structure |
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