Pro*C Interview Question: Difference between Host Variables and Indicator Variables

In Pro*C programming, host variables and indicator variables serve different purposes:

Host Variables

Host variables are used to store values retrieved from the database or to pass values to the database during SQL operations. They can hold data such as strings, numbers, or dates.

Indicator Variables

Indicator variables are used to handle NULL values in database columns. They indicate whether the corresponding host variable contains a valid value or is NULL. Indicator variables are typically associated with host variables when dealing with nullable columns in SQL operations.

Therefore, the main difference between host variables and indicator variables in Pro*C is that host variables store actual data values, while indicator variables provide information about the presence of NULL values in the database columns.