You can embed SQL statements for the database system in programming languages. You can use parameters within SQL statements to specify the values that the programs are to query or save. You declare the parameters as variables (so-called host variables) within the embedding program.
The data type of the host variables is defined when they are declared in the programming language. If possible, the values of the host variables are implicitly converted from the programming language data type to the data type of the database system, and vice versa.
Each parameter can be combined with an indicator variable that indicates irregularities (such as different value and parameter lengths, NULL value, special NULL value, and so on) that may have occurred when the values were assigned. Indicator variables are essential for transferring NULL values and special NULL values. The indicator variables are declared as variables in the embedding program.
SQL Reference Manual, Parameter Name
Concepts of the Database System, Interfaces
The SQL statement parameters are placeholders for variable values. When a user executes an SQL statement containing parameters, the system prompts the user to enter values for the parameters.
See SQL Studio, Setting Parameters for SQL Statements