The ifx_cl_card() function

The ifx_cl_card() function returns the cardinality of the specified collection type host variable.

Syntax

mint ifx_cl_card(collp, isnull)
   ifx_collection_t *collp;
   mint *isnull;

collp: A pointer to the name of the collection host variable in the application.
isnull: Set to 1 if the collection is null, 0 otherwise

Usage

The ifx_cl_card() function enables you to determine the number of elements in a collection, whether the collection is empty, and whether the collection is null.

Return codes

0: The collection is empty.
>0: The number of elements in the collection.
<0: An error occurred.

Example

This sample program is in the ifx_cl_card.ec file in the demo directory.

/*
* Check the cardinality of the collection variable when
* the data is returned from the server
*/

main()
{
        exec sql begin declare section;
        client collection myset;
        exec sql end declare section;
      mint numelems = 0;
        mint isnull = 0;

        exec sql allocate collection ::myset;
        exec sql create database newdb;
        exec sql create table tab (col set(int not null));
        exec sql insert into tab values ("set{}");
        exec sql select * into :myset from tab;
        if ((ifx_cl_card(myset, &isnull) == 0) && isnull == 0)
                printf("collection is empty\n");
        else if ((ifx_cl_card(myset, &isnull) == 0) && isnull == 1)
                printf("collection is null\n");
        else if ((numelems = ifx_cl_card(myset, &isnull))> 0)
                printf("number of elements is %d\n", numelems);
        else
                printf("error occurred\n");

        exec sql update tab set col = ’set{1,2,3}’;
        exec sql select * into :myset from tab;
        if ((ifx_cl_card(myset, &isnull) == 0) && isnull == 0)
                printf("collection is empty\n");

        else if ((ifx_cl_card(myset, &isnull) == 0) && isnull == 1)
                printf("collection is null\n");
        else if ((numelems = ifx_cl_card(myset, &isnull))> 0)
                printf("number of elements is %d\n", numelems);
        else
                printf("error occurred\n");

        exec sql update tab set col = NULL;
        exec sql select * into :myset from tab;
        if ((ifx_cl_card(myset, &isnull) == 0) && isnull == 0)
                printf("collection is empty\n");
        else if ((ifx_cl_card(myset, &isnull) == 0) && isnull == 1)
                printf("collection is null\n");
        else if ((numelems = ifx_cl_card(myset, &isnull))> 0)
                printf("number of elements is %d\n", numelems);
        else
                printf("error occurred\n");
}

Output

collection is empty
number of elements is 3
collection is null