先决条件 – SQL 命令
DELETE是一个数据操作语言 (DML) 命令，用于从关系中删除部分或全部元组。如果 WHERE 子句与 DELETE 命令一起使用，它只删除那些满足 WHERE 子句条件的元组，但如果 DELETE 语句中缺少 WHERE 子句，则默认情况下所有存在于关系中的元组都将被删除。
DELETE 命令的语法：
DELETE FROM relation_name
WHERE condition;DROP是一种数据定义语言 (DDL) 命令，它删除模式的命名元素，如关系、域或约束，您还可以使用 DROP 命令删除整个模式。
DROP 命令的语法：
DROP SCHEMA schema_name RESTRICT;
DROP Table table_name CASCADE;对比图：
| Parameter | DELETE | DROP |
|---|---|---|
| Basic | It removes some or all the tuples from a table. | It removes entire schema, table, domain, or constraints from the database. |
| Language | Data Manipulation Language command | Data Definition Language command. |
| Clause | WHERE clause mainly used along with the DELETE command. | No clause required along with DROP command. |
| Rollback | Actions performed by DELETE can be rolled back as it uses buffer. | Actions performed by DROP can’t be rolled back because it directly works on actual data. |
| Space | space occupied by the table in the memory is not freed even if you delete all the tuples of the table using DELETE | It frees the table space from memory |
| Main Issue | Shortage of memory | Memory fragmentation |
| Locality of reference | Excellent | Adequate |
| Flexibility | Fixed size | Resizing is possible |