Transaction Control Language
The Transaction Control Language (TCL) is that part of a database language that is used to finally transfer the insertions, edits and deletions formulated by data processing commands (DML) into the database. In the SQL database language, these are primarily the commands COMMIT(English for "entrust") to confirm and ROLLBACK(English for "retrieve") to discard all changes summarized in the currently active transaction . Only then will changes be visible outside of the current session .
A separate command for starting a transaction is not provided in the SQL standard. Thus a transaction is implicitly initiated by most of the other preceding statements. Many database systems still offer a command BEGIN TRANSACTIONor START TRANSACTION.
The classification of the transaction commands in a separate category is not standardized and is only used by a few authors and manufacturers, for example by Oracle . Much more often, the transaction commands are assigned to the Data Manipulation Language (DML), and less often to the Data Control Language (DCL).
Individual evidence
- ↑ C. Date, H. Darwen: SQL - The Standard: SQL / 92 with the extensions CLI and PSM , 1998, p. 81.