HP 3000 Manuals

ALLBASE/SQL Pascal Application Programming Guide

Simple Data Manipulation 

In simple data manipulation, you retrieve or insert single rows or update
one or more rows based on a specific criterion.  In most cases, the
simple data manipulation technique is used to support the random
retrieval and/or change of specific rows.

In the following example, if the user wants to perform a DELETE
operation, the program performs the operation only if a single row
qualifies.  If no rows qualify or if more than one row qualifies, the
program displays a message.  Note that the host variables in this case
are designed to accommodate only a single row.  In addition, two of the
columns may contain null values, so an indicator variable is used for
these columns:

     var
          EXEC SQL BEGIN DECLARE SECTION;
          PartNumber       : packed array[1..16] of char;
          PartName         : packed array[1..30] of char;
          PartNameInd      :  sqlInd; 
          SalesPrice       : longreal;
          SalesPriceInd    :  sqlInd; 
          EXEC SQL END DECLARE SECTION;
          .
          .
          .
     procedure DoQuery;
     begin

         This procedure accepts a part number from the user, 
         then executes a query to determine whether one or 
         more rows containing that value actually exists.

       EXEC SQL SELECT  PartNumber, PartName, SalesPrice
                  INTO :PartNumber,
                       :PartName :PartNameInd,
                       :SalesPrice :SalesPriceInd
                  FROM  PurchDB.Parts
                 WHERE  PartNumber = :PartNumber;

       case SQLCA.SQLCODE of
       0           : DisplayDelete;
       100         : writeln('Row not found!');
       -10002      : writeln('WARNING:  More than one row qualifies!');
       otherwise   : SqlStatusCheck;
       end;
       .
       .
       .

     procedure DisplayDelete;

         The qualifying row is displayed for the user to 
         verify that it should be deleted before the following 
         command is executed: 

         EXEC SQL DELETE FROM PurchDB.Parts
                        WHERE PartNumber = :PartNumber;

The chapter, "Simple Data Manipulation," provides more details about
simple data manipulation.

MPE/iX 5.0 Documentation