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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.
A database transaction symbolizes a unit of work, performed within a database management system (or similar system) against a database, that is treated in a coherent and reliable way independent of other transactions. A transaction generally represents any change in a database. Transactions in a database environment have two main purposes:
Modify: Read database values, and tentatively write changes. Validate: Check whether other transactions have modified data that this transaction has used (read or written). This includes transactions that completed after this transaction's start time, and optionally, transactions that are still active at validation time.
Queries, which retrieve the data based on specific criteria. This is an important element of SQL. Statements, which may have a persistent effect on schemata and data, or may control transactions, program flow, connections, sessions, or diagnostics. SQL statements also include the semicolon (";") statement terminator. Though not required on ...
Existing database systems use volatile storage (i.e. the main memory of the system) for different purposes: some store their whole state and data in it, even without any durability guarantee; others keep the state and the data, or part of them, in memory, but also use the non-volatile storage for data; other systems only keep the state in main ...
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
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Codd's twelve rules [1] are a set of thirteen rules (numbered zero to twelve) proposed by Edgar F. Codd, a pioneer of the relational model for databases, designed to define what is required from a database management system in order for it to be considered relational, i.e., a relational database management system (RDBMS).