Understanding the Difference between EXEC SQL DECLARE and EXEC SQL VAR in Pro*C Programming

The focus keyword for this topic is "EXEC SQL DECLARE vs EXEC SQL VAR".

When working with Pro*C programming, it is essential to distinguish between EXEC SQL DECLARE and EXEC SQL VAR statements. These two commands play a crucial role in defining variables for use in SQL queries within Pro*C programs.

EXEC SQL DECLARE

When using the EXEC SQL DECLARE statement in Pro*C programming, you are essentially declaring a host variable that can be used to store data retrieved from a database query. This statement is typically followed by a datatype declaration and variable name specification.

EXEC SQL VAR

On the other hand, the EXEC SQL VAR statement in Pro*C is used to declare and define a variable directly in the SQL query itself. This allows you to specify the variable inline within the SQL statement, without the need for separate host variable declaration.

Distinguishing the use cases

While EXEC SQL DECLARE is more commonly used for declaring host variables that are reused across multiple SQL queries within a Pro*C program, EXEC SQL VAR is useful for defining variables within the context of a specific SQL query.

In summary, the key difference lies in the scope and usage of variables – EXEC SQL DECLARE for host variable declaration and reuse, and EXEC SQL VAR for inline variable definition within SQL queries.