CISC 332 Lecture Notes - Lecture 5: Data Definition Language, Data Integrity, Sql-92
10 Feb 2018
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Document Summary
Sql offered by commercial systems varies o o. Various other features from later standards and proprietary features offered. Sql is a standard but there will be small differences between the sql languages of different. Dbms (so db2 may be a bit different than mysql) The sql ddl allows the specification of info about relations, including: the schema for each relation, the domain of each attribute, integrity constraints o. The set of indicies to be maintained for each relation. Security and authorization info who can access this table. The physical storage structure of each relation on disk. Basic domain types char(n) char string w/ fixed length of n char(10) storing cat 7 spaces are appended to the string to make it. 10 this is a waste of space. Only use if you know the length will always be the same varchar(n) variable length char strings with max length of n varchar(10) soring cat just 3 characters better use of space.
