CS338 Lecture 4: Module 4
10 Feb 2019
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Document Summary
Statements for data definitions queries and updates: ddl & dml. Note: some interfaces need to end each statement with a semi colon. Sql data definition: create, main sql command for data definition, the command used to define things. Includes an authorization identifier (owner: components are descriptors for each schema element, tables, constraints, views, domains and other constructs, create schema statement, eg. Specify a new relation: provide name, specific attributes and initial constraints, base tables / base relations, relation and its tuples are physically stored and managed by dbms, can optionally specify schema, eg. Include information for each column (attribute) plus constraints: column name, column type (domain, key, uniqueness, and null constraints. Basic data types: numeric - integer, floating-point numbers (real), fixed-point numbers (decimal, character-string data types- fixed or varying. Employee table with a nickname column: default province to on. Domains in sql: name used in place of built in data type, easier to change data type used by numerous columns.
