Why do my transactions fail when I invoke executeUpdate()? I've set autocommit to false, but I get the SQLException: "The file is not valid for the operation" and getTransactionIsolation() returns TRANSACTION_UNCOMMITED.
1) A database table.
2) The database must support transactions.
For example, the AS/400 supports transactions via a process called journaling. Journals must be specifically created and operational or SQL Collections, rather than standard libraries, must be created for automatic journals.
To check whether transactions are valid, use DatabaseMetaData.supportsTransactions().