It can be a C structure if called from SQL. Consider:


create or replace function p(p_x in number, p_y in number )
return number
as
begin
return p_x+p_y;
end;
/



static void process()
{
exec sql begin declare section;

typedef struct
{ int x;
int y;
} my_rec;

my_rec data;
int x;
exec sql end declare section;

data.x = 1;
data.y = 2;

EXEC SQL WHENEVER SQLERROR DO sqlerror_hard();
exec sql select p(:data) into :x from dual;

printf( "return value= %d\n", x );
}



that works. Note that it must be a FUNCTION. Also, it cannot have any OUT parameters. Lastly, if it modifies the database, it MUST be an autonomous transaction.

Another method would be:


scott@DEV816> create or replace function p(p_x in OUT number, p_y in OUT number )
2 return number
3 as
4 l_tmp number := p_y;
5 begin
6 p_y := p_x;
7 p_x := l_tmp;
8 return p_x+p_y;
9 end;
10 /

Function created.

scott@DEV816> create global temporary table p_interface_table
2 ( x int, y int, return_code number )
3 on commit delete rows
4 /

Table created.

scott@DEV816> create or replace trigger p_interface_table_trigger
2 BEFORE insert on p_interface_table for each row
3 begin
4 :new.return_code := p(:new.x, :new.y);
5 end;
6 /

Trigger created.



static void process()
{
exec sql begin declare section;

typedef struct
{ int x;
int y;
int return_code;
} my_rec;

my_rec data;
int x;
exec sql end declare section;

data.x = 1;
data.y = 2;

EXEC SQL WHENEVER SQLERROR DO sqlerror_hard();
exec sql insert into p_interface_table values ( :data );

exec sql select * into :data from p_interface_table;

printf( "x, y, return value= %d, %d, %d\n",
data.x, data.y, data.return_code );
}


That lets you do in out variables and does not make you use an autonomous transaction if the procedure/function (you can use either here of course) modifies the database as well.