Visual Basic Global Variables as Query Parameters

Using global variables to pass user selection criteria to queries is a useful programming technique to master.

This Access download will provide you with all the forms, modules, queries and VBA code to get you started.

Here is the SQL query code used in the example:

SELECT M_Student_Courses.Student_ID, L_Students.Student, L_Courses.Course
FROM (M_Student_Courses INNER JOIN L_Students ON M_Student_Courses.Student_ID = L_Students.Student_ID) INNER JOIN L_Courses ON M_Student_Courses.Course_ID = L_Courses.Course_ID
WHERE (((M_Student_Courses.Student_ID)=get_global('gbl_student_id')))
ORDER BY L_Students.Student, L_Courses.Course;

In the code above, get_global is a custom query function that passes back the value of any global variable you have defined.  In this case we are retrieving the GBL_Student_ID which was previously selected as a parameter in the form below.

Note that you can create and use custom vba functions in queries just as you use custom public functions in regular vba code.  These custom function can perform complex recordset operations that are not normally available in access queries.  Complex scalar functions can be implemented with simple vba custom functions.  The get_global function is just a simple example of these query functions.

There are other methods for returning global variables, such as the Eval function, however we find this custom method more reliable and flexible.

Give our Global Variables as Query Parameters downloadable Access example a try.