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SQL refers to Structured Query Language, a kind of language used to access, update and manipulate database. In SQL, ROLLBACK is a command that causes all data changes since the last START TRANSACTION or BEGIN to be discarded by the relational database management systems (RDBMS), so that the state of the data is "rolled back" to the way it was before those changes were made.
In terms of transactions, the opposite of commit is to discard the tentative changes of a transaction, a rollback. The transaction, commit and rollback concepts are key to the ACID property of databases. [1] A COMMIT statement in SQL ends a transaction within a relational database management system (RDBMS
The fundamental similarities between Relational and Object databases are the start and the commit or rollback. After starting a transaction, database records or objects are locked, either read-only or read-write. Reads and writes can then occur.
For systems without a commit/rollback mechanism available, one can undo a failed transaction with a compensating transaction, which will bring the system back to its initial state. Typically, this is only a workaround which has to be implemented manually and cannot guarantee that the system always ends in a consistent state.
COMMIT and ROLLBACK terminate the current transaction and release data locks. In the absence of a START TRANSACTION or similar statement, the semantics of SQL are implementation-dependent. The following example shows a classic transfer of funds transaction, where money is removed from one account and added to another.
Commit Record notes a decision to commit a transaction. Abort Record notes a decision to abort and hence roll back a transaction. Checkpoint Record notes that a checkpoint has been made. These are used to speed up recovery. They record information that eliminates the need to read a long way into the log's past.
This represents a "commit" operation in which the corresponding transaction has successfully completed its preceding actions, and has made all its changes permanent in the database. Alternatively, a schedule can be represented with a directed acyclic graph (or DAG) in which there is an arc (i.e., directed edge) between each ordered pair of ...
All changes made after a savepoint has been declared can be undone by issuing a ROLLBACK TO SAVEPOINT name command. Issuing RELEASE SAVEPOINT name will cause the named savepoint to be discarded, but will not otherwise affect anything. Issuing the commands ROLLBACK or COMMIT will also discard any savepoints created since the start of the main ...