SQL/MX Programming Manual for C and COBOL (G06.24+, H06.03+)

Host Variables in C/C++ Programs

HP NonStop SQL/MX Programming Manual for C and COBOL—523627-004

3-39

C Example of Using INVOKE

The next example declares and uses host variable names and indicator variable

names and shows:

•

A host variable declaration using INVOKE that includes indicator variables. The

structure is declared as global so that any function can reference the host

variables.

•

A host variable indicator variable used in the SELECT statement. The columns that

might contain null require the indicator variable following the host variable to

receive information on nulls.

•

An indicator variable testing for null. If the value of the indicator variable following

the SELECT is less than zero, the associated column is null.

Example 3-3 retrieves four columns of an order detail table. The table is like the

ODETAIL table of the sample database except that the UNIT_PRICE and

QTY_ORDERED columns allow null.

Example 3-3. C INVOKE (page 1 of 2)

...

void handle_null(void);

void display_result(void);

...

EXEC SQL BEGIN DECLARE SECTION;

EXEC SQL INVOKE samdbcat.mysch.odetail;

/* Beginning of generated code for SQL INVOKE */

struct odetail_type {

unsigned long ordernum;

unsigned short partnum;

short unit_price_i;

long unit_price;

short qty_ordered_i;

unsigned long qty_ordered;

} ;

struct odetail_type odetail_rec;

EXEC SQL END DECLARE SECTION;

int main()

{

EXEC SQL BEGIN DECLARE SECTION;

char SQLSTATE[6];

unsigned NUMERIC (6) in_ordernum;

unsigned NUMERIC (4) in_partnum;

EXEC SQL END DECLARE SECTION;

...