Introduction to Relational Databases

Introduction to Relational Databases introduction to data - web developers are self taught. learning HTML and programming. the next step is database integration. databases out of hand - large databases can go crazy when badly designed, leading to poor performance and resulting in a whole new one being needed. database - a collection of related tables. the way they relate is dependent on the model used. early data models - hierarchical model where files are related in a parent or child manner. only one parent file. network models - where files are related as owners and members. similar to the classic model except that each member file can have multiple parents. relational database model - allowed files to be related by means of a common field. very flexible. origination of relational - was seen as impractical as machines weren't ready. SQL - structured query language. a development of relational. easy to learn and allows people to quickly learn how to perform queries on a relational database. data - the values stored in the database. 342449 information - data that is processed to have a meaning. database: definition - a collection of tables tuples - the records in a data table. horizontal rows. fields - part of a record or table. the vertical columns in the table. also called attributes. product record fields characteristics - different types. all have database management systems. three types of fields - character: product description. numeric: quantity. and date: release date domain - refers to the possible values each field can contain. field specification. null value - in a field. when it contai