Using indicator variables

UltraLite Embedded SQL User's Guide
Data Access Using Embedded SQL

Using indicator variables

An indicator variable is a C variable that holds supplementary information about a particular host variable. You can use a host variable when fetching or putting data. Use indicator variables to handle NULL values.

An indicator variable is a host variable of type short int. To detect or specify a NULL value, place the indicator variable immediately following a regular host variable in a SQL statement.

Example

For example, in the following INSERT statement, :ind_phone is an indicator variable.

EXEC SQL INSERT INTO Employee
   VALUES (:employee_number, :employee_name,
   :employee_initials, :employee_phone:ind_phone );

Indicator variable values

The following table provides a summary of indicator variable usage.

Indicator Value	Supplying Value to database	Receiving value from database
0	Host variable value	Fetched a non-NULL value.
-1	NULL value	Fetched a NULL value

Using indicator variables to handle NULL