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Part 4: SQL Persistent Stored Modules
SQL/PSM expands SQL by adding:
lProcedural language extensions
lMulti-statement and Stored Procedures
lExternal function and procedure calls
In addition to being a valuable application development tool, SQL/PSM provides the foundation support for the object oriented capabilities in SQL3.
Multi-statement and Stored Procedures
Multi-statement and stored procedures offer a variety of advantages in a client/server environment:
lPerformance - Since a stored procedure can perform multiple SQL statements, network interaction with the client are reduced.
lSecurity - A user can be given the right to call a stored procedure that updates a table or set of tables but denied the right to update the tables directly
lShared code - The code in a stored procedure does not have to be rewritten and retested for each client tool that accesses the database.
lControl - Provides a single point of definition and control for application logic.
Procedural Language Extensions
Procedural language add the power of a traditional programming language to SQL through flow control statements and a variety of other programming constructs.
Flow Control Statements
lIf-then-else
lLooping constructs
lException handling
lCase statement
lBegin-End blocks
The procedural language extensions include other programming language constructs:
lVariable declarations
lSet statements for value assignment
lGet diagnostics for process and status information
In addition, all of the traditional SQL statements can be included in multi-statement procedures.
External Procedure and Function Calls
One feature frequently mentioned in the wish lists for many database products, and implemented in some, is a capability augmenting the built-in features with calls to user-written procedures external to the database software.
lAllows a particular site or application to add their own database functions
lCan be used throughout the database applications
The benefit of this capability is that it gives the database (and therefore database applications) access to a rich set of procedures and functions too numerous to be defined by a standards committee.
SQL/PSM Timing
SQL/PSM is proceeding quickly:
lSQL/PSM is an addendum to SQL-92
lInternational ballot to progress SQL/PSM from a Draft International Standard to an International Standard ended January, 1996.
lEditing meeting in May, 1996 did not resolve all of the comments
lContinuation of PSM Editing meeting is scheduled for September 30 through October 4, 1996
lThe schedule is tight but there is a chance that PSM will be published with a 1996 date.
lThe official designation will be:
ISO/IEC DIS 9075-4:199? Information technology -- Database languages -- SQL -- Part 4: SQL Persistent
Stored Modules (SQL/PSM)
lWork is well underway on adding SQL/PSM support for SQL3 features.
This page was last updated on July 19, 1996
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