What are the differences between drop and delete?

The difference between drop and delete: 1. Function and purpose; 2. Operation object; 3. Reversibility; 4. Space release; 5. Execution speed and efficiency; 6. Interaction with other commands; 7. Impact persistence; 8. Syntax and execution; 9. Triggers and constraints; 10. Transaction processing. Detailed introduction: 1. Function and purpose. "DELETE" is a data operation language command, mainly used to delete some or all tuples from a table, that is, delete data content. "DROP" is a data definition language command, used to delete data from a table. Delete one from the database and so on.

"DROP" and "DELETE" are two commonly used commands in database management. They have obvious differences in the following aspects:

1. Function and purpose:

• "DELETE" is a data manipulation language (DML) command, mainly used to delete some or all tuples from a table, that is Delete data content. It does not delete the structure of the data table, only affects the data in the table.
• "DROP" is a data definition language (DDL) command used to delete one or more tables from a database. It can delete a table and all its associated data, indexes, triggers, constraints, and permission specifications. Simply put, DROP not only deletes data, but also deletes data structures.

2. Operation object:

• The operation object of "DELETE" is the data table in the database.
• The operation object of "DROP" can be a database or a data table in the database.

3. Reversibility:

• "DELETE" can be used with the WHERE clause to delete records that meet certain conditions. If the WHERE condition is not specified, all records will be deleted. The DELETE operation can be rolled back because it uses buffers.
• The "DROP" operation is not placed in the rollback segment, cannot be rolled back, and the operation does not trigger the trigger.

4. Space release:

• Since "DELETE" does not delete the table, no space will be released.
• "DROP" will delete the entire table, thereby freeing up memory space.

5. Execution speed and efficiency:

• The "DELETE" operation may be slower than "DROP" because it does not release space immediately. More internal processing may be required.
• The "DROP" operation is usually visible immediately and frees up space immediately.

6. Interaction with other commands:

• "DELETE" can be used with the WHERE clause to delete certain conditions. of records; can also be used with the LIMIT clause to limit the number of rows deleted.
• "DROP" cannot be used with any command, it is a more basic database command.

7. Durability of impact:

• The "DELETE" operation only temporarily deletes data. The data is still stored in the database, but is marked as "Deleted" until the transaction commits or a certain time period elapses. This means that in some cases, deleted data can still be recovered.
• The "DROP" operation completely removes data and structures from the database, and the deleted data cannot be recovered.

8. Syntax and execution:

• "DELETE" usually uses simpler syntax and only needs to specify the table to be deleted and possibly condition.
• "DROP" requires more complex syntax because it involves deleting an entire table or database structure.

9. Triggers and constraints:

• The "DELETE" operation may trigger related triggers and constraints when executed.
• The "DROP" operation will delete all related triggers and constraints.

10. Transaction processing:

• The "DELETE" operation can be executed in a transaction, which means that if the transaction fails, what has been done Changes can be undone.
• The "DROP" operation is atomic and cannot be executed within a transaction. Once a "DROP" is performed, either all related tables and structures are dropped, or nothing is dropped.

11. Logging:

• "DELETE" operations are usually recorded in the transaction log, which helps with data recovery and Transaction rollback.
• A "DROP" operation is usually not recorded in the transaction log because it involves deleting an entire table or database structure.

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