VAX Rdb/VMS RDML Reference Manual

This manual serves as a reference for the Relational Data Manipulation Language (RDML) for VAX Rdb/VMS and Rdb/ELN databases. It is intended for programmers who embed RDML statements within C and Pascal programs.

The document outlines the syntax and semantics of all RDML language elements, which are categorized into:

• Value Expressions: Used for calculations, database field references, host language variables, and specific Rdb values (like RDB$DB_KEY and RDB$MISSING).
• Conditional Expressions: Boolean expressions defining relationships between values, used for record selection based on criteria (e.g., ANY, BETWEEN, CONTAINING, MATCHING, MISSING, relational operators, STARTING WITH, UNIQUE).
• Record Selection Expressions (RSEs): Define conditions for records to be included in a temporary "record stream," enabling filtering, duplicate elimination (REDUCED TO), limiting results (FIRST), joining relations (CROSS), and sorting (SORTED BY).
• Statistical Functions: Aggregate functions that calculate a single value from a collection of records in a stream (e.g., AVERAGE, COUNT, MAX, MIN, TOTAL).
• Clauses and Statements: Fundamental components for managing transactions (COMMIT, ROLLBACK, START_TRANSACTION), manipulating records (FETCH, ERASE, MODIFY, STORE), declaring variables (DECLARE_VARIABLE, BASED ON), defining streams (DECLARE_STREAM, START_STREAM, END_STREAM), and handling errors (ON ERROR).

The RDML preprocessor converts these embedded statements into DIGITAL Standard Relational Interface (DSRI) calls. Data definition tasks, however, are handled by other tools like SQL, Relational Database Operator (RDO), or ERDL, as RDML focuses solely on data manipulation. The manual includes numerous C and Pascal programming examples using a sample "PERSONNEL" database.