HP 3000 Manuals

DBChange Plus User's Guide

Getting to Know the DBChange Plus Command Interface 

This section describes the features and operation of the DBChange Plus
command interface.

Command Format 

DBChange Plus commands consist of a command, a keyword, and parameters.
For a complete list of commands, keywords, and acceptable abbreviations,
refer to Table 10-1.

Figure 1-1 illustrates the various parts of a typical DBChange Plus
command.


          Figure 1-1.  Typical DBChange Plus Command Format 

For more information about DBChange Plus command formats, refer to the
"Command Formats" section in chapter 10, "DBChange Plus Commands."

Difference Between Deferred and Immediate Commands 

DBChange Plus has two types of commands:  immediate and deferred.

Immediate commands are those commands that do not affect the database
structure, but instead give information about or help with the operation
of the DBCPLUS program.  They are executed immediately when they are
entered.  The following are immediate commands:

   *   BASE
   *   CANCEL
   *   CONTROL
   *   EXIT
   *   HELP
   *   OUTPUT
   *   PERFORM COMMANDS
   *   PRINT
   *   RECOVER
   *   REDO
   *   REVIEW
   *   XEQ

Deferred commands are those commands that are stored in the change file
and take effect upon execution of the DBAPLUS program.  The following are
deferred commands:

   *   ADD
   *   CHANGE
   *   CHECK
   *   DELETE
   *   ERASE
   *   FIX
   *   RENAME
   *   REORDER
   *   REPACK

Command Sequence 

The DBAPLUS program executes deferred commands in the order that most
effectively protects your data and most efficiently handles your data
throughput.  For example, if the current change file contains a CHECK
command, some ADD and DELETE commands, a FIX command, and a CHANGE
command, DBAPLUS executes the commands in the following order:

   1.  CHECK

   2.  FIX

   3.  Other commands

Terminating a Command 

You can cause the DBCPLUS program to ignore the command you are currently
entering by typing two slashes (//) and pressing the carriage return key.
This returns you to the DBChange prompt (>).  You might use this feature,
for example, if you decide not to execute the current command or if you
make an error and want to start over.

For example:

     >change it// 
     >

This feature is only available in interactive mode.

Executing Commands from a File 

You can execute DBChange Plus commands from a file in the following two
ways:

   *   Use a command file to make database changes interactively or in
       batch mode.  This is useful if you frequently use the same
       sequence of commands.  To use a command file in batch mode, it
       must be executed from a job file.

   *   Use a job file to run DBChange Plus in batch mode.  This is useful
       if you want to make changes to the database at a later time.  You
       can include command files in a job file.

Including Comments in a File.   

In a command file or job file, if you want to include DBChange comments,
enclose them in double angle brackets, for example, << comment>>.  In the
MPE command portion of a job file, the word comment at the beginning of a
line indicates that the text on that line constitutes a comment.

Using a Command File.     

A command file is a series of DBChange Plus commands and parameters.
When the XEQ command is entered, DBChange Plus reads the specified
command file and executes the commands until it reaches the end of the
file.  After DBChange Plus reads the last line in the command file,
control is returned to the original command input device (the user
terminal interactively or the the job input device in batch mode).  If
the command file contains the EXIT command, DBChange Plus terminates and
the system prompt appears on your screen.

The following command file CMDFILE deletes the data item DATE, changes
the capacity of the manual master data set CUSTOMER to 450, and exits the
DBCPLUS program.

The XEQ command executes the command file CMDFILE as follows:

     >xeq cmdfile 

     ><<This command file creates a new change file for the>>

     ><<ORDERS database, deletes the data item DATE, and>>

     ><<changes the capacity of the manual master data set>>

     ><<CUSTOMER to 450.>>

     >base orders new                       <---- DBChange command 

      Change file already exist for ORDERS, do you want to purge it [y/N] ? y 
      Change file ORDERSCF has been purged.

      Creating new change file:

      Creating new change file: item information records

      Creating new change file: set information records

      Creating new change file: security table

      Creating new change file: control record

     >delete item date                      <---- DBChange command 

      Deletion of data item accepted.

     >change capacity customer 450          <---- DBChange command 

      Change of set capacity, block factor, and/or device class  accepted.

     >exit                                  <---- DBChange command 

      Please wait ... change file is being verified.

     HP36386 (A.00.00) DBCHANGE  (c) COPYRIGHT Hewlett-Packard Co. 1985

     ******************* DBCHANGE STATISTICS***************************

                Number of databases prepared for rename:       0
                Number of databases prepared for restructure:  1
                Number of databases prepared for erase :       0
                Number of databases prepared for repack:       0
                Number of databases prepared for check :       0
                Number of databases prepared for fix   :       0

     :

Using a Job File.     

A job file is a text file that contains DBChange Plus and MPE XL
commands.  A job file is used in batch mode.  Command files can be
included in a job file.  In the following example, the job DBCJOB
executes some MPE XL commands, some DBChange commands, and the command
file CMDFILE, which was explained in the previous example.  Note that the
command file CMDFILE contains the EXIT command.

     !job dbcjob,kelly/user.finance/mgr.database/all
     comment**  Show time and date dbcjob begins
     !showtime
     !run dbcplus.pub.sys
     base orders new
     change password CLERK AGENT
     xeq cmdfile
     comment**  Show time and date dbcjob ends
     !showtime
     !tell kelly.finance.database dbcjob is done
     !eoj

For more information about job files and streaming jobs, refer to
"Creating a DBAPLUS Job File from within the DBChange Program" in chapter
9, "Applying Changes to the Database Structure."

Issuing MPE XL Commands from within the DBCPLUS Program 

Many MPE XL commands, including RUN commands, can be entered
interactively.  You can issue MPE XL commands from within the DBCPLUS
program either by entering a colon (:)  after the DBCPLUS prompt and then
typing the command, or by using Break and RESUME. In the following
example, at the DBCPLUS prompt (>) a colon is entered and the MPE XL
LISTF command is issued:

     >:listf 

     FILENAME

     ORDERS      ORDERS01    ORDERS02    ORDERS03    ORDERS04    ORDERS05
     ORDERS06    ORDERSCF    ORDERSJJ    PCHGFMT     TESTDB      TESTDB01
     TESTDB02    TESTDB03    TESTDB04    TESTDB05    TESTDBCF    TESTDBCO

     HP36386 (A.00.00) DBCHANGE  (c) COPYRIGHT Hewlett-Packard Co. 1985

     >

If you press Break to access MPE XL, type the MPE XL command RESUME when
you are ready to return to the DBCPLUS program.  When READ PENDING is
displayed, press Return and the DBChange prompt reappears.  For example:

     Break 
     :listf 

     FILENAME

     ORDERS      ORDERS01    ORDERS02    ORDERS03    ORDERS04    ORDERS05
     ORDERS06    ORDERSCF    ORDERSJJ    PCHGFMT     TESTDB      TESTDB01
     TESTDB02    TESTDB03    TESTDB04    TESTDB05    TESTDBCF    TESTDBCO
     :resume 
     READ pending

     Return 
     >


CAUTION  Using Break while running the DBAPLUS program or after issuing a
         PERFORM COMMANDS can result in a damaged database.

MPE/iX 5.0 Documentation