Tuple

5.1 Tuple Relational Calculus Language ALPHA - Update Operations (1) Modification Operations with UPDATE Statement The steps to execute an update operation in ALPHA are as follows: Use the HOLD statement: Initially, retrieve the tuple to be modified from the database into the workspace using the HOLD statement. Modify attributes in workspace: Modify the attributes of the tuple in the workspace using the host language. Send modified tuple back with UPDATE: Finally, use the UPDATE statement to send the modified tuple back into the database. Important Notes: For simple data retrieval, the GET statement can be used directly. However, to retrieve tuples specifically for modification, you must use the HOLD statement. This statement is a concurrent control-enabled version of GET. Concurrency control details will be further elaborated in Chapter 5.