How to start a transaction in JDBC?
I suggest you read this you'll see
Therefore, the first call of setAutoCommit(false) and each call of commit() implicitly mark the start of a transaction. Transactions can be undone before they are committed by calling
Edit:
Check the official documentation on JDBC Transactions
When a connection is created, it is in auto-commit mode. This means that each individual SQL statement is treated as a transaction and is automatically committed right after it is executed. (To be more precise, the default is for a SQL statement to be committed when it is completed, not when it is executed. A statement is completed when all of its result sets and update counts have been retrieved. In almost all cases, however, a statement is completed, and therefore committed, right after it is executed.)
The way to allow two or more statements to be grouped into a transaction is to disable the auto-commit mode. This is demonstrated in the following code, where con is an active connection:
con.setAutoCommit(false);
Source: JDBC Transactions
JDBC implicitly demarcates each query/update you perform on the connection with a transaction. You can customize this behavior by calling setAutoCommit(false) to turn off the auto-commit mode and call the commit()/rollback() to indicate the end of a transaction. Pesudo code
try
{
con.setAutoCommit(false);
//1 or more queries or updates
con.commit();
}
catch(Exception e)
{
con.rollback();
}
finally
{
con.close();
}
Now, there is a type in the method you have shown. It should be setTransactionIsolation(int level) and is not the api for transaction demarcation. It manages how/when the changes made by one operation become visible to other concurrent operations, the "I" in ACID (http://en.wikipedia.org/wiki/Isolation_(database_systems))
Answering my own question:
- JDBC connections start out with auto-commit mode enabled, where each SQL statement is implicitly demarcated with a transaction.
- Users who wish to execute multiple statements per transaction must turn auto-commit off.
- Changing the auto-commit mode triggers a commit of the current transaction (if one is active).
Connection.setTransactionIsolation()
may be invoked anytime if auto-commit is enabled.- If auto-commit is disabled,
Connection.setTransactionIsolation()
may only be invoked before or after a transaction. Invoking it in the middle of a transaction leads to undefined behavior.
See JDBC Tutorial by Oracle.