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SQL Anywhere 10.0.1 » UltraLite - C and C++ Programming » Developing Applications Using Embedded SQL » Using host variables

Using host variables in C++ Next Page

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