The Operating System and UniVerse - SQL Database

UniVerse is one group of programs that runs in the UNIX or Windows operating system environment. However, because the operating system environment can be invisible to the end user, UniVerse can be perceived as the operating environment. UniVerse has its own command processor, with a command vocabulary that includes some operating system commands and many data management commands that cannot be accessed from the operating system. UniVerse also has its own login procedure and account structure.

Although you can do almost everything from UniVerse, a good understanding of the operating system enhances your use of UniVerse. UniVerse System Description explains the processes, utilities, and commands that you use when working in the UniVerse environment.

UniVerse Tables

Tables are implemented as UniVerse files. Every UniVerse table logically comprises one data table and an associated table dictionary. Data tables contain columns that store data values in cells. Each data table also contains an encrypted area called the security and integrity constraints area (SICA) that stores the table’s column definitions, integrity constraints, and access permissions. Table dictionaries contain records that define the contents of data tables, as well as the way data is processed and displayed.

The relationship between a data table and its associated dictionary is defined by an entry in the VOC (vocabulary) file that defines the table. Table dictionary records do the following:

  • Define columns in the associated data table
  • Define different descriptors for data stored in the same column
  • Process data stored in columns
  • Translate data from other tables
  • Define output specifications and report formats

Rows in UniVerse tables are of variable length; so are the columns that make up the rows. The only limit to the number of rows that can be stored in a table is the size of your hard disk. Each row is identified by a unique key called the record ID.

UniVerse File Structure

UniVerse tables and files are implemented using operating system directories and files. UniVerse provides several kinds of file organization. This variety of storage methods simplifies application design and provides superior performance.
The following structures are available:

  • Type 1 and type 19 files (nonhashed)
  • Static hashed files
  • Dynamic files
  • B-tree files

A data table can be either nonhashed or hashed, depending on the kind of data you want to store. Unless otherwise specified, tables are created as dynamic UniVerse files. Table dictionaries are usually hashed.

The VOC File

UniVerse SQL Statements and Commands Each UniVerse schema has a vocabulary file called the VOC file. The VOC file contains entries that identify every command, keyword, table, and file that you can use while you are in that schema. The command processor uses the VOC file to determine what action to take when you enter a statement. UniVerse contains an account called UV that is used for system administration. When a schema or

UniVerse account is created, the contents of a file called NEWACC in the UV account are copied to the VOC file in the newly created schema or account. This ensures that every new schema and account begins with a correct standard set of commands, sentences, paragraphs, file names, keywords, and menus. You can tailor the copied VOC file to the specified purposes of the schema by adding synonyms for standard commands and keywords, or storing often-used statements

UniVerse SQL Statements and Commands

When you enter the UniVerse environment, the command processor displays a prompt (>). You now can enter any SQL statement or UniVerse command.

For example, when you enter the following statement, the UniVerse command processor looks up SELECT in the VOC file:
>SELECT * FROM ENGAGEMENTS.T;

Since SELECT * FROM is an SQL statement, control is passed to UniVerse SQL to execute the sentence.

You can store any statement for future use by creating a stored sentence record in the VOC file. You can also store a sequence of statements by creating a paragraph entry. Stored sentences and paragraphs let you repeat a statement or a sequence of statements often.

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