
        By William F. Slater, III
        Colorado Springs, CO


                          PARADOX SQL LINK Version 4.0

                             ***  A PREVIEW  ***

       INTRODUCTION

       Along with the release of PARADOX 4.0 for DOS, BORLAND has also
       released new versions PARADOX SQL LINK 4.0 for each of the server
       databases it worked with previously, plus a few new ones.  PARADOX SQL
       LINK is BORLAND's strategic client/server PC product which will permit
       PARADOX to act as a powerful front-end to several different types of
       relational, SQL-based server databases.


       WHAT IS CLIENT/SERVER?

       To begin with, this would be a good point to give a definition of
       client/server:  A software and hardware configuration which divides
       processing efforts between desktop and server platforms.  Database
       operations are performed by a database management system typically on
       a larger server platform, while other operations such as data entry,
       queries, graphs, and editing are performed on the smaller desktop
       platform.  In this case, the database server would be an SQL-based
       database management system, such as Rdb/VMS and the clients would be
       PCs which will be running front-end software such as PARADOX with SQL
       LINK (Rdb/VMS) which permits client/server connectivity to Rdb/VMS.


       MY FAVORITE SERVER DATABASE

       Because I work for Digital Equipment Corporation, I have unlimited,
       ready access to Rdb/VMS running on VAX 6000 series and VAX 8000 series
       computers.  I also have some access to ORACLE server databases, but I
       prefer to work with Rdb/VMS because it is my personal favorite server
       database.  This is the reason that all of my SQL LINK articles always
       feature Rdb/VMS as the server database.

       SQL LINK BACKGROUND

       SQL LINK was first released by BORLAND in September 1990, and when it
       was installed, it combined with PARADOX 3.5 to give users
       client/server access to SQL-based relational server databases.
       Originally the server databases which SQL LINK would "talk" to were MS
       SQL SERVER, ORACLE, and IBM EE DB MANAGER OS/2.  In February  1991, a
       special SQL LINK version which would work with Digital's VAX Rdb/VMS
       was released.  Later, in 1991, an 1.1 version for the other server
       databases (but not for Rdb/VMS) was released.  Now, expected for
       release in June or July 1992, SQL LINK version 4.0 will be released.

       1.0 or 1.1 -> 4.0

       But what happened to SQL LINK versions 2.0 and 3.0?  Did we miss
       something?  No.  Those versions could never be released because they
       were eaten by Godzilla. (Just kidding!)  No, actually SQL LINK 1.0
       (for Rdb/VMS) and 1.1 should now be upgraded to SQL LINK 4.0 if you
       plan to have client/server functionality between PARADOX 4.0 for DOS
       and any of the server databases which SQL LINK supports.  I should
       mention here that your 1.0 and 1.1 versions of SQL LINK will only work
       with PARADOX 3.5 and are not upwardly compatible with PARADOX 4.0 for
       DOS.  BORLAND decided to synchronize release numbers of PARADOX and
       SQL LINK to avoid confusion about compatibility of this and future
       versions.


       IMPROVEMENTS IN SQL LINK - Replica Dictionaries and the SQL Editor

       Replica Dictionaries

       Replica Dictionaries are easier to set up.  There is a very useful
       dictionary build options where SQL LINK will permit the user to select
       table names based on a using a "@" for a name wildcard option.  For
       example, a user could select all table names which begin with the
       string "TIME" by specifying TIME@@@@@@@@@@@ .  This will save time in
       building the replica dictionary because it allows the user to be more
       selective.  The user will find this wildcard option particularly
       useful as he/she accesses a server database with a large number of
       tables.  Another option which must be looked at with some caution is
       the option which permits the building of replica tables which are
       based on "system" tables from the server database.  The "system"
       tables contain detailed information which is used internally my
       Rdb/VMS to manage an Rdb database.   When I attempted the building of
       these replica tables which would be based on Rdb system tables, they
       built successfully; however what I found when I executed a QBE query
       on these tables was that they contained Rdb/VMS data types which are
       not recognizable by PARADOX.  Though time did not permit me to test
       this as much as I wanted, I came to the conclusion that this option to
       build replica tables based on the server database system tables may
       not be as useful (or as necessary) as one might think.

       See the screen below for an example of these options.

       (See Screen SP4_02.COM)
       (See Screen SP4_03.COM)
       (See Screen SP4_04.COM)


       In addition to these Replica options, there are two other interesting
       features that are included with SQL LINK version 4.0.  The first is
       the capability to generate a "Replica report"; and the second is
       the capability to track what problems there were during the creation
       of replica tables in the PARADOX table called SQLPROBS.  SQLSETUP will
       display SQLPROBS automatically if there were any problems during the
       Replica creation process.


       (See Screen SP4_05.COM)



       USESQL - The SQL Editor

       The SQL Editor, which is invoked by playing the script named
       USESQL.SC which is located in the \PDOX40 directory named USESQL.SC
       has some new features which make it easier to use.  Three of these
       features are a "clipboard" for temporarily storing blocks of code, a
       "card" feature, which permits the storing and selection of SQL 
       statements from a descriptive list that includes server information and 
       who the creator was, and the importing of blocks of SQL statements.  
       Note that if you want to import an SQL statement into the SQL Editor, 
       which was produced has been saved under the SQLSave option for a 
       QBE query on the PARADOX desktop, from the SQL LINK menu, you will have 
       to do two things:  1) rename the .SC file comtaining the SQL 
       statement to a .SQL file, and 2) remove the SQL command at the top and 
       the ENDSQL command at the bottom.  These are PAL SQL extensions, and 
       cannot be use in the context of the SQL Editor.  Overall, however, if 
       you liked the SQL Editor in the SQL LINK 1.0 or 1.1 products, you will 
       enjoy using the PARADOX SQL LINK 4.0 SQL Editor.

       (See Screen SP4_SE1.COM)
       (See Screen SP4_SE2.COM)
       (See Screen SP4_SE3.COM)
       (See Screen SP4_SE5.COM)


       WHAT YOU NEED TO GET STARTED USING PARADOX SQL LINK 4.0  WITH Rdb/VMS
       TO USE SQL LINK

       In order to use SQL LINK 4.0, you must have the following installed at
       your site (the server requirements for VAX Rdb/VMS have been included
       below):

       Client Requirements

        A.  Make sure your IBM compatible PC has:

            1.  a network card (for PATHWORKS connections)

            2.  PARADOX 4.0 already installed

            3.  PARADOX SQL LINK for Rdb/VMS vers. 1.0 or greater (Note:
                many users will have accidentally bought the PARADOX SQL
                LINK which operates with other SQL server databases.  Be
                sure you buy the correct flavor of PARADOX SQL LINK.)

            4.  PATHWORKS 4.0 or greater.

            5.  About 4.5 MB of hard disk space for software.
                PARADOX 4.0 requires about 4.0 MB, and PARADOX SQL LINK
                requires 750 KB of hard disk space.

            6.  At least 2MB of RAM

            7.  MS-DOS 3.3 or greater

            8.  Additional hard drive space for Rdb table
                downloads ( a fast hard drive is desirable )

            9.  A 80286, 80386, or 80486 processor (a fast 80386
                or 80486 is recommended)

       Server Requirements

            1.  Any VAX which runs VAX/VMS

                Note: If a MicroVAX or VAX 3100 is used, a minimum of
                a two disk drive configuration is strongly recommended
                for performance reasons.

            2.  VMS 5.3 or greater

            3.  Rdb/VMS 4.0A or greater

            4.  PATHWORKS for VMS must be currently running

            5.  Connection to the PC network card

            6.  SQL Services process currently running

            7.  A username account set up for the remote user

            8.  An Rdb database to connect to and retrieve
                records from, copy tables to, or to operate
                with in an SQL LINK (client-based) turn-key
                application.

       NEW PAL SQL EXTENSION COMMAND

       There is a new PAL SQL extension included in the new SQL LINK
       4.0.  It is briefly described below:


          SHOWSQL  -  Performs the same function as pressing [Alt] [F2]
                      when a QBE query is on the workspace.

       FUNCTIONALITY

       You will find the characteristic look and feel of PARADOX 4.0 for DOS
       is present throughout your use of SQL LINK 4.0.  That is because the
       products, once installed together behave as a single product which
       just happens to have client/server functionality along with all the
       standard PARADOX features for local tables.

       (See Screen SP4_06.COM)

       QUERIES

       Through the use of client-initiated queries using QBE syntax or SQL
       statements, the SQL LINK user may have sets of data copied right into
       the client PC, into an answer table.  Table joins are possible for
       retrieving related data from more than one table at a time, however,
       for the initial query, all tables must reside on the same platform.
       That is to say that one cannot directly join data from a server table
       to a local table.  If this were necessary, the server data would have
       to be copied to the PC first, or else the PC table would have to
       be copied to the server database first.  Note that DELETE and
       CHANGETO queries are also possible.  In order to make PARADOX SQL LINK
       as a valuable SQL learning tool, the user may want to either use the
       {Tools} {SQL} {SQLSave} to save the QBE query as a PARADOX script
       which will have SQL statements in it.   Note that the query must be
       physically on the workspace for this to be successful.  The other
       method that the user can use to learn SQL is to press the [Alt] [F2]
       keys together while a QBE query which is on the desktop.  The
       equivalent SQL statement immediately appears in the center of
       the screen for the user.  Remember that any QBE statement can be saved
       as an SQL Statement in a PARADOX script file.

       Note these examples shown below:

       (See Screen SP4_Q1.COM)
       (See Screen SP4_Q1A.COM)
       (See Screen SP4_Q1B.COM)
       (See Screen SP4_Q2.COM)
       (See Screen SP4_Q3.COM)
       (See Screen SP4_Q3B.COM)
       (See Screen SP4_Q4.COM)
       (See Screen SP4_Q5.COM)
       (See Screen SP4_Q6.COM)
       (See Screen SP4_Q7.COM)
       (See Screen SP4_Q8.COM)

       SQLSETUP

       The SQLSETUP script is still used under SQL LINK 4.0 to invoke the
       server connection options, and to help control building of replica
       dictionaries.  The steps to get a connection to Rdb/VMS are outlined
       below:

       To get an Rdb database connection do this:

                {Tools} {SQL} {Connection} {Select}

                Press [F2] to select the Rdb/VMS connection setting from the
                SQL Connection List Screen.  It will be the only setting on
                the list.

                Then you must provide VAX/VMS server signon information in
                the connection screen that appears:


                           REMOTE USER      :  ______________

                           REMOTE PASSWORD  :  ______________

                           REMOTE NODENAME  :  ______________

                           SCHEMA NAME      :  ______________


                Fill in the appropriate information and press the [F2] key.
                If you did everything correctly, a message in the lower
                right part of the screen will indicate:  "Rdb/VMS"

                Don't forget to execute SQLSETUP to build your replica
                dictionary!



       SAMPLE APPLICATION

       RUNNING THE SAMPLE CLIENT/SERVER APPLICATION

       Note that each time a user wishes to execute the sample
       application, the SQL connection process will have to occur.

       The sample application is a fine example of what a PARADOX SQL LINK
       user can expect to experience when running a turn-key system
       which is PC-based but interfaces directly with Rdb/VMS on a VAX.
       Although the user's screens and keyboard will have the look and
       feel of the same PC executing PARADOX, that they have been used
       to, the user will indeed be interfacing with a very powerful
       relational database management system on the VAX.

       To become familiar with the capabilities of the sample
       application, the user should try the following capabilities of
       the sample application:

                           1.  Insert records

                           2.  Delete Records

                           3.  Modify Records

                           4.  Execute Queries

                           5.  Run Reports


       Note that while the sample application is similar to the sample
       application in operation and in table structures, the sample
       application menu and the functions are very different.  There is no
       menu all stretched out on the workspace when the application
       executes.  The sample application only has four options on it, and the
       menu uses the old "SHOWMENU-style" of menu.

     POSSIBLE USES OF PARADOX SQL LINK 4.0

         1.  Downloading data from Rdb/VMS to PARADOX

         2.  Uploading data from PARADOX to Rdb/VMS

         3.  Client/server turn-key system access

         4.  Get Rdb/VMS data into PARADOX format for easy import to
             QUATTRO PRO.  One the data is in QUATTRO PRO format, if
             it is in tabular format, it can be easily graphed and turned
             into presentation quality graphics.

         5.  Database Administration Uses

               A)  The rapid creation of a DBA table which contains the name
                   of every table which is defined in an Rdb schema file and
                   easily modifying this table with other fields and data
                   which will permit a more automated method of managing the
                   DBA details of the database.

               B)  Using the table described above with PARADOX report
                   writer to have PARADOX rapidly generate hundreds of lines
                   of SQL schema DML code in seconds.  This includes schema
                   code for defining storage areas, maps, and indexes.

               C)  Using PARADOX SQL LINK to create and populate tables into
                   a test Rdb database by copying PARADOX tables up to an Rdb
                   schema file on a VAX.

               D)  "Quickie" database conversions using two different copies
                    of PARADOX SQL LINK.


       CONCLUSION

       The folks at BORLAND have again produced a powerful client/server
       tool which is helping users achieve the goal of implementing
       client/server solutions using server database, while allowing them to
       retain the familiar PARADOX front-end, as they work with full-fledged
       server data (back-end) on the client platform.  Bravo, BORLAND!

       If you are an SQL LINK customer who is considering the purchase of SQL
       LINK 4.0 to use with PARADOX 4.0 and your server database, get the
       purchase order out because you will be very pleased with both the SQL
       LINK functionality and performance.  If you are a new SQL LINK user
       and you are interested in client/server functionality between PARADOX
       and your favorite server database for which SQL LINK has some
       connectivity, then by all means give it a try.   I'm sure you will
       like what you find out about using PARADOX SQL LINK with any good
       server database.


    --------------------------------------------------------------------
    Reprinted with permission from PARADOX Informant.  Copyright (c) 1992
    Informant Communications Group.  All rights reserved.  Unauthorized
    reproduction and/or revision prohibited.

    -------------------------------------------------------------------------
    Note:  This article contains information which was printed in the June
           1992 issue of PARADOX INFORMANT.  For additional information
           contact the PARADOX INFORMANT at 916-686-6610, and ask for Mitch
           Koulouris or Jerry Coffey.  I highly recommend PARADOX INFORMANT
           as the finest PARADOX monthly technical publication on the planet.

           William F. Slater, III
    -------------------------------------------------------------------------
    Reprinted with permission from PARADOX Informant.  Copyright (c) 1992
    Informant Communications Group.  All rights reserved.  Unauthorized
    reproduction and/or revision prohibited.
