| A | B |
|---|
| Master File | A permanent file of records that reflects the current status of relevant business items such as inventory and accounts receivable. The master file is updated with the latest transactions from the current transaction file. |
| Data Dictionary | An ordered collection of data elements that is essentially a centralized source of data about data. Each data element used in the organization is a record in the data dictionary that contains data about that data element. |
| Transaction File | A relatively temporary data file containing transaction data that are typically used to update a master file. |
| Data Definition Language (DDL) | A database management system language that ties the logical and physical view of the data together. |
| Database | A set of interrelated, centrally controlled data files that are stored with as little data redundancy as possible. |
| Data Manipulation Language (DML) | A database management system language that is used to update, replace, store, retrieve, insert, delete, sort, and otherwise manipulate the records and data items in the database. |
| Database Management System (DBMS) | The specialized computer program that manages and controls the data and interfaces between the data and the application programs. |
| Data Query Language (DQL) | A high-level English-like command language that is used to interrogate a database. |
| Database System | The combination of the database, the database management system, and the application programs that access the database through the database management system. |
| Report Writer | Software that lets a user specify the data elements to be printed. The report writer searches the database, extracts the desired items, and prints tham out in the user-specified format. |
| Logical View | The manner in which users conceputally organize, view, and understand the relationships among data items. Contrast with physical view. |
| Data Model | An abstract representation of the contents of a database. |
| Physical View | The way data are physically arranged and stored on disks, tapes, and other storage media. EDP personnel use this view to make efficient use of storage and processing resources. Contrast with logical view. |
| Relational Data Model | A database model in which all data elements are logically viewed as being stored in the form of two-dimensional tables called "relations." |
| Record Layout | A document that illustrates the arrangement of items of data in input, output, and file records. |
| Relations | The tables used to store data in a relational database. |
| Tuple | A row in a relation. A tuple contains data about a specific occurrence of the type of entity represented by that database table. (pronounced to rhyme with the word couple). |
| Schema | A description of the types of data elements that are in the database, the relationships among the data elements and the structure or overall logical model used to organize and describe the data. |
| Primary Key | A unique identification code assigned to each record within a system. The primary key is the key used most frequently to distinguish, order, and reference records. |
| Conceptual-Level Schema | The organization-wide schema of the entire database. It lists all data elements in the database and the relationships between them. Contrast with external-level schema and internal-level schema. |
| Foreign Key | An attribute appearing in one table that is itself the primary key of another table. |
| External-Level Schema | An individual user's or application program's view of a subset of the organization's database. Each of these individual user views is also referred to as a subschema. Contrast with conceptual-level schema and internal-level schema. |
| Entity Integrity Rule | A design constraint in a relational database, requiring that the primary key have a non-null value. This ensures that a specific object exists in the world and can be identified by reference to its primary key value. |
| Subschema | (1) A subset of the schema that includes only those data items used in a particular application program or by a particular user. (2) The way the user defines the data and the data relationships. |
| Referential Integrity Rule | A constraint in relational database design requiring that any non-null value of a foreign key must correspond to a primary key in the referenced table. |
| Internal-Level Schema | A low-level view of the entire database describing how the data are actually stored and accessed. It includes information about pointers, indexes, record lengths, and so forth. Contrast with external-level schemas and conceptual-level schemas. |
| Normalization | The process of following the guidelines for properly designing a relational database that is free from delete, insert, and update anomalies. |
