[EMAIL PROTECTED] wrote on 08/03/2005 10:20:36 AM: > What is a schema? How is different from a database? >
As I understand it, and some scholars may disagree with me, a schema is (most often) a description of a data structure. A database IS a data structure composed of tables and other possible components like views, stored procedures, triggers, etc. When we talk about schemas, we have to qualify the discussion with the level of the description you want to make. A table schema will detail the design of a table. It will have the column names, their data types, any default values, any constraints, any indexes (keys) etc. A database schema would discuss the details of the contents of a particular database. It would include things like the table names, where they are stored (for tables stored in different folders or on separate media), any relationships between the tables, and things at that level. Application level schemas would include such higher-level concepts as server names and the databases on them, other data sources (files, web streams, etc). So while some database systems (Oracle? I don't recall which.) identify the "database" level of data organization as a "schema" the more general use of the term is in the context of providing the physical description (the plan or scheme) of an organizational level. As I said, that's how I use the term and others will definitely have other opinions. Shawn Green Database Administrator Unimin Corporation - Spruce Pine
