Chapter 3 Concise History of SQL IFS Intro. to Data Management

History of DBMS Hierarchical Database Structure Where structure is formed by data groups, subgroups, and further subgroups Strength – capturing and storing transactional data Major weakness – difficult for ad-hoc or on- demand queries

History of DBMS DEPT # Dept Name Reports To Manager Budget Emp # Emp Name Dept # Sex Salary Grade Job# Job Description Job Date Title Child Name Age Sex Salary Date Salary System / Program had to navigate forward / backward thru branches

History of DBMS Network Database Structure Developed to allow retrieval of specific records Utilizes a system of ‘Pointers’ (RRN’s) No longer had to follow branches Major weakness – maintenance of Pointers

History of DBMS Extremely Fast for Querying Data, Slow for TPS

History of DBMS Relational DBMS – 1970 Codd & Date Based Upon relational algebra and Set Theory from 1800’s. Sets of object are considered as a whole Relational algebra (simplest form) are truth tables. And / Or / Nor Fast ad-hoc queries and TP

History of SQL English like Query Language was developed to manipulate data in RDBMS (structured query language) Relational Software (aka Oracle) Cal Berkley (INGRES) IBM (DB/2)

History of SQL American National Standards Institute (ANSI) SQL Standard: YearNameAliasComments 1986SQL-86SQL-87First published by ANSI. Ratified by ISO in 1987.ANSIISO1987 Lacked Referential Integrity 1989SQL-89Minor revision. 1992SQL-92SQL2Major revision. Focusing on Standardization 1999SQL:19 99 SQL3Added regular expression matching, recursive queries, triggers, non-scalar types and some object-oriented features. (The last two are somewhat controversial and not yet widely supported.) 2003SQL:20 03 Introduced XML-related features, window functions, standardized sequences and columns with auto-generated values (including identity-columns). (See Eisenberg et al.: SQL:2003 Has Been Published.)Eisenberg et al.: SQL:2003 Has Been Published

History of SQL Even though SQL is a standard, all major vendors have their version Oracle = PL/SQL IBM = SQL PL Microsoft = Transact SQL

History of SQL Why so many versions of SQL Implementations? Size / Complexity of ANSI Standard Missing components from STD (Indexing) Ambiguity of standard Backwards compatibility Need to be careful and know what vendor you are working with