Camis - Transact-SQL

Definitions

Stored procedures are a bit like methods. Here's a brief description with examples from W3 Schools.
# is used for temporary local tables. ## is used for global temporary tables. (Stack Overflow)
- If you don't see your changes to a stored procedure, it's possible that it's only been passed into a temporary table and not the final (returned) result.
@ is used to indicate variables (including parameters).
BEGIN...END defines a block to contain statements that execute together. (Microsoft Learn: BEGIN…END)
SET NOCOUNT can be OFF (default) or ON. When on, it disables messages sent to the client for every statement executed (for example, the “N rows affected” message). (Microsoft Learn: SET NOCOUNT)
SET TRANSACTION ISOLATION LEVEL: setting the level determines what violations are allowed or not. ( Microsoft Learn: SET TRANSACTION ISOLATION LEVEL)

SQL vs Transact-SQL (Dataquest blog)
- Transact-SQL is developed and owned by Microsoft (has all SQL features and some extra)
ACID transactions: Atomicity, Consistency, Isolation, Durability
- Seems to be a set of principles for how transactions (should) behave
- Devopedia explanation of ACID Transactions
  - Atomicity: All-or-nothing changes. If there's a failure mid-transaction, everything is rolled back to the state prior to the transaction start.
  - Consistency: Only valid data is saved (even if invalid mid-transaction).
  - Isolation: Transactions do not affect each other. The intermediate state of a transaction is not visible to other transactions.
  - Durability: Written data won't be lost. When a transaction completes, the changes are stored in a persistent manner (that power failure or other system errors won't affect).