Tag: technology

To know in your Java program that a SQL warning is generated as a result of executing a SQL statement in the database, you must invoke the getWarnings() method on the Statement object (or a sub interface). Therefore, option C is the correct answer.

Option A is incorrect because SQLException is thrown when an SQL error occurs, not a warning. It is a checked exception and must be caught or declared to be thrown.

Option B is incorrect because SQLWarningException is not a valid exception class in Java. SQLWarning is the class that represents a warning issued by the database.

Option D is incorrect because ResultSet object is used to retrieve data from the database after executing a query, not to retrieve warnings.

Therefore, the correct answer is:

The Answer is: C. O (c) You must invoke the getWarnings() method on the Statement object (or a sub interface).

To answer this question, the user needs to have knowledge about ResultSets and their characteristics.

Option A is incorrect because there is no openCursor() method in the ResultSet class.

Option B is partially correct. The ResultSet object is updateable only if you indicate a concurrency strategy when executing the statement, and the driver supports updateable ResultSets.

Option C is incorrect because there is no class called UpdateableResultSet in the Java API.

Option D is incorrect because ResultSets can be updateable, but it depends on the driver, the type of ResultSet, and the concurrency strategy used.

Therefore, the correct answer is:

The Answer is: B

To understand the meaning of the transaction isolation level TRANSACTION_REPEATABLE_READ, we need to know about transaction isolation levels in database management systems.

Transaction isolation level is a concept that ensures the correctness and consistency of database transactions. It defines the level of isolation between concurrent transactions in the system.

The TRANSACTION_REPEATABLE_READ isolation level guarantees that during the transaction, any row that is read will be locked for the duration of the transaction. This means that if the transaction tries to read the same row again, it will get the same value as before. This ensures that the transaction sees a consistent snapshot of the data.

Now let's go through each option to see which one is correct:

A. (a) Dirty reads, non-repeatable reads, and phantom reads can occur - This option is incorrect. The TRANSACTION_REPEATABLE_READ level prevents dirty reads and non-repeatable reads, but phantom reads can still occur.

B. (b) Dirty reads are prevented; non-repeatable reads and phantom reads can occur - This option is incorrect. The TRANSACTION_REPEATABLE_READ level prevents dirty reads, but non-repeatable reads and phantom reads can still occur.

C. (c) Dirty reads and non-repeatable reads are prevented; phantom reads can occur - This option is correct. The TRANSACTION_REPEATABLE_READ level prevents dirty reads and non-repeatable reads, but phantom reads can still occur.

D. (d) Dirty reads, non-repeatable reads, and phantom reads are prevented - This option is incorrect. The TRANSACTION_REPEATABLE_READ level only prevents dirty reads and non-repeatable reads, but phantom reads can still occur.

Therefore, the answer is: C. (c) Dirty reads and non-repeatable reads are prevented; phantom reads can occur.

The correct answer is A. You can execute a stored procedure in the database by calling the execute() method on a CallableStatement object.

Explanation:

A stored procedure is a precompiled set of SQL statements that are stored in the database. To execute a stored procedure, you need to create a CallableStatement object, which allows you to call the stored procedure.

Here's an example of how to execute a stored procedure using Java and JDBC:

// Assuming you have already established a database connection
CallableStatement cstmt = conn.prepareCall("{call your_stored_procedure(?, ?)}");

// Set any input parameters for the stored procedure, if needed
cstmt.setString(1, "input_parameter1");
cstmt.setInt(2, 2);

// Execute the stored procedure
cstmt.execute();

In the code above, your_stored_procedure is the name of the stored procedure you want to execute. The ? placeholders are used for any input parameters the stored procedure may require. You can set the input parameters using the setXxx() methods on the CallableStatement object.

Lastly, you call the execute() method on the CallableStatement object to execute the stored procedure.

To answer this question, the user needs to have a basic understanding of Java Database Connectivity (JDBC) and ResultSet objects.

Option A is incorrect. The close() method does exist for ResultSet objects.

Option B is correct. If you call the close() method on a ResultSet object, the resources associated with the ResultSet will be released and returned to the database. This includes any database and JDBC resources that were used to create the ResultSet.

Option C is incorrect. The close() method can be called on a ResultSet object, but not on a Statement object. It is the Statement object that creates the ResultSet.

Option D is incorrect. While the ResultSet is associated with the Statement and Connection objects that created it, calling the close() method on the ResultSet will only release the resources associated with the ResultSet itself, not the Statement or Connection objects.

Therefore, the answer is: B. O (b) the database and JDBC resources are released.