GEOG372 Lecture Notes - Lecture 9: Spatial Database, Data Definition Language, Relational Database
31 Oct 2016
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Document Summary
Relational database comprises a set of tables, each a 2d list or array of records containing attributess about the objects under study. Keys -> each row contains a key (usually fields can be/are keys) -> allows for. Relation= set of records that have same attributes. Standard database query langage adopted by virtually all maiinstream databases is structred query langugage. Dml (data maniplative language) used to retrieve and manipulate data. Ddl (data definition language) used to create , alter, and delete relational database structures. Dcl ( data control language) handle authorization and access. Only one value in each cell at intersection of a row and column. All values in a column are about the same subject (field) There is no significance to the sequence of columns. There is no significant to the sequence of rows. Object : a variable, data structure, function, or method, that has a value and is referenced by an identifier.
