Oracle Rdb - Data Access

Data Access

Interactive access to the Oracle Rdb can be by SQL (Structured Query Language), RDO (Relational Database Operator), or both.

High level languages usually access Oracle-Rdb by:

  1. embedding RDO statements in the source file then running it through a precompiler
    (example: "file.RCO" is pre-compiled into "file.COB")
  2. embedding SQL statements in the source file then running it through a precompiler
    (example: "file.SCO" is pre-compiled into "file.COB")
  3. placing the SQL statements in a file external to the source code; this separate file is converted to object code by the "SQL Module Language" compiler, and the source code then references these SQL statements and, after compilation, the two are joined by the OpenVMS linker.
example: $ SQL$MOD file_bas.sqlmod -> file_bas.obj $ BASIC file.bas -> file.obj $ LINK file.obj,file._bas.obj -> file.exe

A variation of example 3 allows "Dynamic SQL" to be created in the source code, and then used to communicate with Rdb via a structure known as SQLDA (SQL Descriptor Area).

On OpenVMS systems, Oracle Rdb is a popular (although expensive) upgrade path for applications written using Record Management Services (RMS) files.

Read more about this topic:  Oracle Rdb

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