Oracle Corporation is asking for community feedback on the SQL-92 CREATE ASSERTION feature. If you would like them implemented in Oracle Database, please vote at https://community.oracle.com/ideas/13028 (click on the up-arrow). Yuu need to log into your OTN account in order to vote. If you do not have an OTN account, please consider registering for one. Backgrounder The creator of the relational model, Dr. Codd touted its simplicity and consequent appeal to users—especially casual users—who have little or no training in programming. He singles out this advantage in the opening sentence of his first paper on relational theory A Relational Model of Data for Large Shared Data Banks : “Future users of large data banks must be protected from having to know how the data is organized in the machine (the internal representation).” He made the point more forcefully in a subsequent paper, Normalized Data Base Structure: A Brief Tutorial in which he says: “In the choice of logical data structures that a system is to support, there is one consideration of absolutely paramount importance—and that is the convenience of the majority of users. … To make formatted data bases readily accessible to users (especially casual users) who have little or no training in programming we must provide the simplest possible data structures and almost natural language. … What could be a simpler, more universally needed, and more universally understood data structure than a table? Why not permit such users to view all the data in a data base in a tabular way?” But the true importance of the relational model is highlighted by the title Derivability, Redundancy, and Consistency of Relations Stored in Large Data Banks of the unpublished original—and shorter—version of Dr. Codd’s paper which predated the published version by a year. That title hints that the chief advantage of the relational model is its ability it gives us to assert arbitrarily-complex consistency constraints that must be satisfied by the data within the database; that is, the ability to put the “C” into “ACID.” An example of a complex constraint is: A pilot may fly a certain type of aircraft only if (1) he has flown that type of aircraft previously or (2a) he has attended a training class on flying that type of aircraft and (2b) the instructor of that class is one of the co-pilots. Oracle Rdb for the OpenVMS operating system already provides the SQL-92 CREATE ASSERTION specification ( http://community.hpe.com/hpeb/attachments/hpeb/itrc-149/22979/1/15667.doc ) so why not Oracle Database? Let’s put the “C” into “ACID.” We’ve waited 25 years but better late than never. References CREATE ASSERTION: The Impossible Dream? (NoCOUG Journal, August 2013) RuleGen 3.0: Data Quality Assurance (NoCOUG Journal, August 2013) CREATE ASSERTION: Neither Impossible nor a Dream (NoCOUG Journal, November 2013) Postscript The relational model shields both programmers as well as casual users from the physical representation of data. Should programmers be protected from having to know how the data is organized in the machine? Will they develop high-performance applications if they are ignorant of the physical representation?
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