Using arrays of host structures in C and C++ applications that use SQL

In C and C++ programs, you can define a host structure array that has the dimension attribute. Host structure arrays have a maximum of two levels, even though the array might occur within a multiple-level structure. Another structure is not needed if a varying-length character string or a varying-length graphic string is not used.

In this C example,

struct {
       _Packed struct{
                      char c1_var[20];
                      short c2_var;
                     } b_array[10];
       } a_struct;

and in this C++ example,

#pragma pack(1)
struct {
       struct{
                      char c1_var[20];
                      short c2_var;
                     } b_array[10];
       } a_struct;
#pragma pack()

the following are true:

All of the members in b_array must be valid variable declarations.
The _Packed attribute must be specified for the struct tag.
b_array is the name of an array of host structures containing the members c1_var and c2_var.
b_array may only be used on the blocked forms of FETCH statements and INSERT statements.
c1_var and c2_var are not valid host variables in any SQL statement.
A structure cannot contain an intermediate level structure.

For example, in C you can retrieve 10 rows from the cursor with:

_Packed struct {char first_initial;
                char middle_initial;
                _Packed struct {short lastname_len;
                                char lastname_data[15];
                               } lastname;
                double total_salary;
               } employee_rec[10];
struct { short inds[4];
       } employee_inds[10];
…
EXEC SQL DECLARE C1 CURSOR FOR
 SELECT SUBSTR(FIRSTNME,1,1), MIDINIT, LASTNAME,
              SALARY+BONUS+COMM
         FROM CORPDATA.EMPLOYEE;
EXEC SQL OPEN C1;
EXEC SQL FETCH C1 FOR 10 ROWS INTO :employee_rec:employee_inds;
…