SQL/MX Programming Manual for C and COBOL (H06.10+, J06.03+)

Introduction

HP NonStop SQL/MX Programming Manual for C and COBOL—544617-003

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Declaring and Using Host Variables

modify the eld options to link the application to a DLL instead of an executable. For

more information, see the DLL Programmer’s Guide for TNS/E Systems.

For efficient management of module files, SQL/MX allows the modules to be

located with the corresponding DLLs.

The module files are managed in the following sequence:

1. When the application is executed, SQL/MX automatically identifies the location of

all the DLLs loaded by the application.

2. SQL/MX searches for module files in the locations in the following order:

a. location of the executable program

b. location of the DLL

c. system global module directory called /usr/tandem/sqlmx/USERMODULES

3. SQL/MX loads the module files from all the DLL locations. While loading the

module files, if SQL/MX finds a module that matches the specified name, it stops

searching the module files.

Declaring and Using Host Variables

Host variables are host language variables declared in a host language program and

used in both host language statements and embedded SQL statements. You use host

variables to provide communication between 3GL and SQL statements—to receive

data from a database or to insert data into a database. A host variable can be any valid

host language variable that has a corresponding SQL data type.

Declaring Host Variables

Declare host variables in a Declare Section in the variable declarations part of your

program. A Declare Section begins with BEGIN DECLARE SECTION and ends with

END DECLARE SECTION.

Example

In this example, hv_this_customer and hv_custname are host variables:

EXEC SQL BEGIN DECLARE SECTION;

unsigned NUMERIC (4) hv_this_customer; /* host variables */

char hv_custname[19];

EXEC SQL END DECLARE SECTION;

Note. When DLLs are loaded from multiple locations, the order of search is not defined.

Note. You must ensure that the module file names are unique across the locations of all

the DLLs.