HP 3000 Manuals HP 3000 Manuals
Database Description Language
The database description, called a schema, can exist in the MPE/iX system
as an ASCII file. Regardless of the actual physical record size of the
file, the Schema Processor reads, prints, and processes only the first 72
characters of each record. Any remaining character positions in the
record are available for your convenience, to be used for comments or
collating information. The database description language is a
free-format language; you can insert blanks anywhere in the schema to
improve its appearance, except within symbolic names and reserved words.
Language Conventions
The conventions used in describing the database language are the same as
those described on the conventions page at the beginning of this manual.
In addition, the conventions in Table 3-1 apply.
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Table 3-1. Additional Conventions
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| | |
| Convention | Description |
| | |
------------------------------------------------------------------------------
| | |
| Punctuation | All punctuation appearing in format statements must |
| | appear exactly as shown. |
| | |
------------------------------------------------------------------------------
| | |
| Comments | Comments take this form: <<comment>> |
| | |
| | Comments can contain any characters and can appear |
| | anywhere in the schema except embedded in another |
| | comment. They are included in the schema listing but are |
| | otherwise ignored by the Schema Processor program. |
| | |
------------------------------------------------------------------------------
| | |
| Data Names | Data names can consist of from 1 to 16 alphanumeric |
| | characters, the first of which must be alphabetic. |
| | Characters after the first must be chosen from this set: |
| | |
| | |
| | Letters A through Z, digits 0 through 9, or + - * / ? ' |
| | # % & @ |
| | |
------------------------------------------------------------------------------
| | |
| Upshifting | All alphabetic input to the Schema Processor is upshifted |
| | (converted to uppercase) with the exception of passwords |
| | which can contain lowercase characters. Because the |
| | Schema Processor upshifts alphabetic characters, programs |
| | must specify data set and data item names in all |
| | uppercase characters. Take note of this if the |
| | programming language you use does not require uppercase |
| | characters. |
| | |
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Schema Structure
The overall schema structure is:
BEGIN DATABASE database name[,LANGUAGE: language];
PASSWORDS: password part
ITEMS: item part
SETS: set part
END.
The database name is an alphanumeric string from 1 to 6 characters. The
first character must be alphabetic.
The language is the native language definition name or number for the
database. Refer to the Native Language Support Programmer's Guide for
further information. The default language is NATIVE-3000 which uses the
US ASCII character set.
The password part, item part, and set part are described on the following
pages. Figure 3-5 contains a complete schema for the ORDERS database
used in the examples in this manual.