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Procedure
Abstract
Required_Reading
Keywords
Brief_I/O
Detailed_Input
Detailed_Output
Parameters
Exceptions
Files
Particulars
Examples
Restrictions
Literature_References
Author_and_Institution
Version
Index_Entries

Procedure

   SpiceInt eknelt_c ( SpiceInt  selidx,
                       SpiceInt  row     ) 

Abstract

 
   Return the number of elements in a specified column entry in 
   the current row. 
 

Required_Reading

 
   EK 
 

Keywords

 
   EK 
 

Brief_I/O

 
   Variable  I/O  Description 
   --------  ---  -------------------------------------------------- 
   selidx     I   Index of parent column in SELECT clause. 
   row        I   Row containing element. 
   
   The function returns the number of elements in entry in current row. 
 

Detailed_Input

 
   selidx         is the SELECT clause index of the column to 
                  fetch from.  The range of selidx is 0 : (nsel-1)
                  inclusive, where nsel is the number of items in
                  the SELECT clause of the current query.
 
   row            is the index of the row containing the element. 
                  This number refers to a member of the set of rows 
                  matching a query.  row must be in the range 
 
                    0 : nmrows-1 
 
                  where nmrows is the matching row count returned 
                  by ekfind_c. 
 

Detailed_Output

 
   The function returns the number of elements in the column entry 
   belonging to the specified column in the current row. 
 
   Null entries in variable-size columns are considered to have size 1. 
 

Parameters

 
   None. 
 

Exceptions

 
   1)  If this routine is called when no E-kernels have been loaded, 
       the error SPICE(NOLOADEDFILES) is signalled. 
 
   2)  If selidx is outside of the range established by the 
       last query passed to ekfind_c, the error SPICE(INVALIDINDEX) 
       will be signalled. 
 
   3)  If row is outside of the range established by the 
       last query passed to ekfind_c, the error SPICE(INVALIDINDEX) 
       will be signalled. 
 

Files

 
   At least one E-kernel must be loaded before queries may be passed to
   the EK system via ekfind_c.
 

Particulars

 
   This routine is meant to be used in conjunction with the EK 
   fetch entry points ekgc_c, ekgd_c, and ekgi_c.  This routine 
   allows the caller of those routines to determine appropriate 
   loop bounds to use to fetch each column entry in the current row. 
 

Examples

 
   1)  Suppose the EK table TAB contains the following columns: 
 
 
          Column name   Data Type   Size 
          -----------   ---------   ---- 
          IARRAY        INT         10 
          DARRAY        DP          VARIABLE 
          CARRAY        CHR         VARIABLE 
 
 
       Suppose the query 
 
          QUERY = "SELECT IARRAY, DARRAY, CARRAY FROM TAB" 
 
       is issued to ekfind_c via the call 
 
          ekfind_c ( query, MSGLEN, &nmrows, &error, errmsg );
 
       To fetch and dump column values from the rows that satisfy the 
       query, the loop below could be used.  Note that we don't check 
       the FOUND flags returned by the fetch routines since we know 
       in advance how many elements are contained in each column 
       entry we fetch. 
 
             #include <stdio.h>
             #include "SpiceUsr.h"
             
             #define ISIZE  10
                    .
                    .
                    .
             
              for ( row = 0;  row < nmrows;  row++ )
             {
                printf ( "\nROW  =  %d\n\n", row );
 
                /.
                Fetch values from column IARRAY in the current 
                row.  Since IARRAY was the first column selected, 
                the selection index SELIDX is set to 0. 
                ./
                selidx = 0;
                eltidx = 0;
                isnull = SPICEFALSE;
                
                while (  ( eltidx < ISIZE ) && ( !isnull )  )
                {
                    /.
                   If the column entry is null, we'll be kicked 
                   out of this loop after the first iteration. 
                   ./
                   
                   ekgi_c ( selidx,         row,      eltidx, 
                             ivals[eltidx],  &isnull,  &found );

                   eltidx++; 
                }
                
                printf ( "\nCOLUMN  =  IARRAY\n\n" );
 
                if ( isnull )
                {
                    printf ( "<Null>\n" );
                }
                else
                {
                    for ( i = 0;  i < ISIZE;  i++ )
                   {
                       printf ( "%d\n", ivals[i] );
                   }
                }
 
                /.
                Fetch values from column DARRAY in the current 
                row.  Since DARRAY contains variable-size array 
                elements, we call eknelt_c to determine how many 
                elements to fetch. 
                ./
 
                selidx = 1;
                eltidx = 0;
                nelt   = eknelt_c ( selidx, row );
                isnull = SPICEFALSE;
                
                while (  ( eltidx < nelt ) && ( !isnull )  )
                {
                    /.
                   If the column entry is null, we'll be kicked 
                   out of this loop after the first iteration. 
                   ./
                   
                   ekgd_c ( selidx,         row,      eltidx, 
                             dvals[eltidx],  &isnull,  &found   );

                   eltidx++; 
                }
                
                printf ( "\nCOLUMN  =  DARRAY\n\n" );
 
                if ( isnull )
                {
                    printf ( "<Null>\n" );
                }
                else
                {
                    for ( i = 0;  i < nelt;  i++ )
                   {
                       printf ( "%f\n", dvals[i] );
                   }
                }
 
                /.
                Fetch values from column CARRAY in the current row. 
                ./
 
                selidx = 2;
                eltidx = 0;
                nelt   = eknelt_c ( selidx, row );
                isnull = SPICEFALSE;
                
                while (  ( eltidx < nelt ) && ( !isnull )  )
                {
                    /.
                   If the column entry is null, we'll be kicked 
                   out of this loop after the first iteration. 
                   
                   CVLEN is the declared length of the strings in
                   the cvals array.
                   ./
                   
                   ekgc_c ( selidx,        row,     eltidx, CVLEN, 
                             cvals[eltidx], &isnull, &found         );

                   eltidx++; 
                }
 
                printf ( "\nCOLUMN  =  CARRAY\n\n" );
 
                if ( isnull )
                {
                    printf ( "<Null>\n" );
                }
                else
                {
                    for ( i = 0;  i < nelt;  i++ )
                   {
                       printf ( "%s\n", cvals[i] );
                   }
                }
 
             } 
 
 

Restrictions

 
   None. 
 

Literature_References

 
   None. 
 

Author_and_Institution

 
   N.J. Bachman   (JPL) 
 

Version

 
   -CSPICE Version 1.1.0, 23-JUL-2001 (NJB)
     
      Removed tab characters from source file.

   -CSPICE Version 1.0.0, 24-FEB-1999 (NJB)

Index_Entries

 
   return the number of elements in a column entry 
 
Wed Apr  5 17:54:33 2017