Q121. Statement for assigning privileges?
`GRANT`. To remove: `REVOKE`. ```sql GRANT SELECT, INSERT ON database.orders TO 'app_user'@'%'; REVOKE DELETE ON database.orders FROM 'app_user'@'%'; ```
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Q122. Types of privileges?
1. **System privileges**: CREATE, DROP, ALTER (database-level) 2. **Object privileges**: SELECT, INSERT, UPDATE, DELETE, EXECUTE (table/procedure-level)
Q123. Privileges a user can grant?
In SQL security management, database administrators can grant specific privileges using the `GRANT` statement: - **Data Manipulation Privileges**: `SELECT`, `INSERT`, `UP...
Q124. What is SQL Injection?
A code injection attack where malicious SQL is inserted via user input. Prevention: 1. **Parameterized queries** (prepared statements) 2. **Input validation** 3. **ORM fr...
Q125. What does "locking" refer to?
A mechanism to prevent concurrent transactions from interfering with each other. Locks can be **shared** (read locks, multiple allowed) or **exclusive** (write locks, onl...
Q126. Main transaction controls?
- `COMMIT` — Make changes permanent - `ROLLBACK` — Undo all changes in the transaction - `SAVEPOINT` — Set a partial rollback point ```sql START TRANSACTION; UPDATE accou...
Q127. A transaction that completes execution is said to be?
A database transaction that finishes all operations successfully and persists its changes permanently to durable storage is said to be **Committed**: ```sql START TRANSAC...
Q128. What does ROLLBACK do after COMMIT?
**`ROLLBACK` does nothing after a `COMMIT` has executed**. ### Why? Once a transaction issues `COMMIT`, the changes are permanently written to the database transaction lo...
Q129. Valid properties of a transaction?
The four foundational properties that guarantee database transactions are processed reliably are known as **ACID**: 1. **Atomicity**: "All or nothing." If any statement w...
Q130. What if autocommit is enabled?
Every individual statement is automatically committed. In MySQL, autocommit is ON by default. Turn it off for multi-statement transactions: ```sql SET autocommit = 0; -- ...