1. A control device for accessing a database system, the control device comprising: a memory configured to store a user program and definition information, the user program including a structure type of variable, the definition information indicating a definition of the structure type included in the user program; a generator configured to read the definition information and, on the basis of the read definition information, generate a SQL statement to be used when access to the database system is made by execution of the user program; and an execution unit configured to execute the generated SQL statement by transmitting the SQL statement to the database system.