16.20 - C Function Definition - Advanced SQL Engine - Teradata Database

Teradata Vantage™ - SQL External Routine Programming

Product
Advanced SQL Engine
Teradata Database
Release Number
16.20
Release Date
April 2020
Content Type
Programming Reference
Publication ID
B035-1147-162K
Language
English (United States)
#define SQL_TEXT Latin_Text
#include <sqltypes_td.h>
#include <string.h>

typedef struct agr_storage {
	int cr;    // current rank
	int pv;    // previous value
} AGR_Storage;

void dense_rank( FNC_Phase       phase,
                 FNC_Context_t  *fctx,
                 INTEGER        *x,
                 INTEGER        *result,
                 int            *x_i,
                 int            *result_i,
                 char            sqlstate[6],
                 SQL_TEXT        fncname[129],
                 SQL_TEXT        sfncname[129],
                 SQL_TEXT        error_message[257] )
{
	/* pointer to intermediate storage area */
	AGR_Storage *s1 = fctx->interim1;

	/* switch to determine the aggregation phase */
	switch (phase)
	{
		case AGR_INIT:
		/* This UDF currently handles only the cumulative window */
		/* type for illustrative purposes.                       */
		if (fctx->window_size != -1)
		{
			strcpy(error_message,"Only cumulative window type supported");
			strcpy(sqlstate, "U0001"); /* see SQLSTATE table */
			return;
		}
		if ( (s1=FNC_DefMem(sizeof(AGR_Storage))) == NULL)
		{
			strcpy(sqlstate, "U0002");
			return;
		}
		s1->cr = 1;
		s1->pv = *x;

		/***************************************************/
		/* Fall through to the detail phase                */
		/***************************************************/

		case AGR_DETAIL:
		if (*x != s1->pv)
		{
			s1->cr++;
			s1->pv = *x;
		}
		break;

		case AGR_FINAL:
		   *result = s1->cr;
		break;

         /* Add this to generate an error for any undefined phases */
		case AGR_COMBINE:
		case AGR_MOVINGTRAIL:
		default:
		   sprintf(error_message,"phase is %d",phase);
		   strcpy(sqlstate, "U0005");
		return;
      }
}