April 2026
Beginner
493 pages
23h 2m
English
Content preview from SQL
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6.2 Why Is Transaction Control Language Necessary?
As stated earlier, TCL stands for transaction control language. To understand the necessity of TCL, we need to understand the core term transaction first.
A transaction is a sequence of SQL operations (such as INSERT, UPDATE, and/or DELETE) that make up a single unit. This unit is treated as an atomic operation, meaning that all operations in the sequence must either succeed or cancel altogether if any operation fails.
Rollbacks (undoing) are one of the significant benefits of TCL. As a tangible example from our Daisy Bank playground, imagine a stored procedure that conducts a money transfer between two accounts. That procedure needs to conduct a transaction made up of three operations:
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