SLR23 Databases Flashcards
Entity relationship diagram
“A data modelling technique that graphically illustrates an information system’s entities and the relationships between those entities. An ERD is a conceptual and representational model of data used to represent the entity framework infrastructure.”
Attribute
“A single bit of data within a record.”
Primary key
“A field that uniquely identifies a record in a table.”
Composite primary key
“When more than one field is added together to form a unique primary key for a table.”
Foreign key
“The linking field in the foreign table formed when a relationship is made. The FK becomes by default the PK of the new table.”
Normalisation
“The process of arranging data in tables and setting their relationships to move them through normal forms.”
0NF
“A table with no normalisation. All data and all fields in one table.”
1NF
“A relationship with repeating groups removed; a relation in which the intersection of each tuple and attribute contains one and only one value.”
2NF
“A relation that is in 1NF; every non-primary key attribute is fully dependant on the primary key and all the incomplete dependencies have been removed”
3NF
“A relation that is in 1NF and 2NF; no non-primary key attribute is transitively dependant on the primary key and all non-key elements are fully dependant on the primary key.”
Structured Query Language
“The language and syntax used to write and run database queries.”
Relational database
“Allows the user to specify information about multiple tables and the relationship between those tables.”
“A data modelling technique that graphically illustrates an information system’s entities and the relationships between those entities. An ERD is a conceptual and representational model of data used to represent the entity framework infrastructure.”
Entity relationship diagram
“A single bit of data within a record.”
Attribute
“A field that uniquely identifies a record in a table.”
Primary key
