1. JavaScript Short Answer Questions
List the differences between Java and JavaScript?
Java is a very complete and mature programming language. In contrast, JavaScript is a programming language that can be incorporated into HTML pages. The two languages are not completely interdependent, but are designed for different intents. Java is an object-oriented programming or structured programming language like C++ or C, while JavaScript is a client-side scripting language, which is called unstructured programming.
2. MySQL short answer questions
What are the four characteristics and meanings of database transactions?
Atomicity: All operations in the entire transaction are either completed or not completed, and it is impossible to stagnate at a certain link in the middle. If an error occurs during the execution of the transaction, it will be rolled back (Rollback) to the state before the transaction started, as if the transaction was never executed.
Consistency: The integrity constraints of the database are not violated before the transaction begins and after the transaction ends.
Isolation: An isolated state executes transactions so that they appear to be the only operations the system performs at a given time. If there are two transactions, running at the same time and performing the same function, the isolation of the transaction will ensure that each transaction in the system thinks that only that transaction is using the system. This property is sometimes called serialization. To prevent confusion between transaction operations, requests must be serialized or serialized so that only one request is for the same data at a time.
Persistence: After the transaction is completed, the changes made by the transaction to the database are persisted in the database and will not be rolled back.
3. Java Short Answer Questions
What is the mechanism for implementing polymorphism in Java?
The reference variable defined by the parent class or interface can point to the instance object of the subclass or the specific implementation class, and the method called by the program is dynamically bound at runtime. The method here refers to the method of the specific instance object pointed to by the reference variable. It is the method of the object that is running in memory, not the method defined in the type of the reference variable.