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Database Glossary

Relational Database Design & Microsoft Access Glossary:

  • Atomic The smallest meaningful value
  • Attribute An attribute is a characteristic or property of an ENTITY. In relational database terminology an attribute usually means a column or FIELD in a table
  • AutoNumber The AutoNumber data type stores an integer that Access increments (adds to) automatically as you add new records. You can use the AutoNumber data type as a unique record identification for tables having no other unique value.
  • Boyce-Codd normal form A table is in third normal form (3NF) and all determinants are candidate keys
  • Business Rule A business operation reflected in the design of a database
  • Candidate Key A field or fields that qualifies as a Primary Key
  • Cyclic Dependency Occurs when there is a multi-field primary key with three or more fields (for example, fields A, B, C) and those fields are related in pairs of A and B, B and C, and A and C
  • Database A group of tables holding related information
  • Deletion Anomaly Inability to delete unwanted data without deleting data that you need to retain
  • Denormalise To intentionally create tables with data that is not normalised, usually done for performance purposes
  • Determinant A field in which the value determines the value in another field
  • Entity An entity is a single object about which data can be stored. It is the "subject" of a table. Entities and their interrelationships are modeled through the use of entity-relationship diagrams
  • ER Diagram A graphical representation of the tables (entities) in a database and the relationships between them
  • Field A column of data about all the records
  • Fifth Normal Form A table is in fourth normal form (4NF) and there are no cyclic dependencies
  • First Normal Form A table in in first normal form (1NF) if there are no repeating groups
  • Foreign Key The Primary Key from one table is added to another table so the records can be related
  • Fourth Normal Form A table is in Boyce-Codd normal form (BCNF) and there are no multi-valued dependencies
  • Functional Dependency A relationship between fields such that the value in one field determines the one value that can be contained in the other field
  • Inner Join A join of two tables that returns records for which there is a matching value in the field on which the tables are joined
  • Insertion Anomaly Inability to add new records or values without creating data problems such as blank values
  • Intersection Table A table added to the database to break down a many-to-many relationship to form two one-to-many relationships
  • Many-To-Many Relationship A relationship between two tables in which many records in one table can be related to many records in the other table
  • Modification Anomaly Inability to accurately and efficiently maintain data
  • Multi-field Primary Key A combination of two or more fields that uniquely identifies an individual record
  • Multi-valued dependency (MVD) Occurs when, for each value in field A, there is a set of values for field B and a set of values for field C but fields B and C are not related
  • Natural Join An inner join in which redundant columns are eliminated
  • Non-key Field A field that is not part of a foreign or primary key
  • Normal Forms Standards for the design of tables in a relational database
  • Normalisation The process of decomposing large tables into smaller ones in order to eliminate redundant data and duplicate data.
  • Null A missing or unknown value
  • One-To-Many Relationship A relationship between two tables in which one record in one table potentially can be related to many records in another table
  • One-To-One Relationship A relationship between two tables in which each record in one table relates to a maximum of one record in the other table
  • Orphan Record A record in a related or child table with no matching record in the primary or parent table
  • Outer Join A join between two tables that returns all the records from one table and, from the second table, only those records in which there is a matching value in the field on which the tables are joined
  • Primary Key A field or fields that hold values that are unique to each record
  • Primary Table The table on the one side of a one-to-many relationship
  • Record A row of data about a single item
  • Related Table The table on the many side of a one-to-many relationship
  • Relational Database Data stored in a structure of rows and columns
  • Relational Database Management System (RDBMS) A software application that utilizes a relational database model to hold the data used in the application
  • Repeating Group A set of logically related fields or values that occur multiple times in one record
  • Second Normal Form A table is in first normal form (1NF) and each non-key field is functionally dependent on the entire primary key
  • Self Join The Self-Join is a join that relates data in a table to itself. A table is joined to itself based upon a field or combination of fields that have duplicate data in different records. The data-type of the inter-related columns must be of the same type.
  • SQL Structured Query Language (SQL) is both the International Organization for Standardization (ISO) and the American National Standards Institute (ANSI) standard language for creating, updating and querying relational database management systems (RDBMS).
  • Table Rows and columns of data about a single subject
  • Third Normal Form A table is in second normal form (2NF) and there are no transitive dependencies
  • Transitive Dependency A type of functional dependency in which the value in a non-key field is determined by the value in another non-key field and that field is not a candidate key
  • Value A single piece of data