Indicator variables are C variables that hold supplementary information when you are fetching or putting data. There are several distinct uses for indicator variables:
NULL values To enable applications to handle NULL values.
String truncation To enable applications to handle cases when fetched values must be truncated to fit into host variables.
Conversion errors To hold error information.
An indicator variable is a host variable of type short int that is placed immediately following a regular host variable in a SQL statement. For example, in the following INSERT statement, :ind_phone is an indicator variable:
EXEC SQL INSERT INTO Employees VALUES (:employee_number, :employee_name, :employee_initials, :employee_phone:ind_phone );
Using indicator variables to handle NULL
Using indicator variables for truncated values
Using indicator values for conversion errors
Summary of indicator variable values