Prerequisite – SQL Commands
DELETE is a Data Manipulation Language (DML) command and used when you want to remove some or all the tuples from a relation. If WHERE clause is used along with the DELETE command it removes only those tuples which satisfy the WHERE clause condition but if WHERE clause is missing from the DELETE statement then by default all the tuples present in relation are removed.
The syntax of DELETE command:
DELETE FROM relation_name WHERE condition;
DROP is a Data Definition Language (DDL) command which removes the named elements of the schema like relations, domains or constraints and you can also remove an entire schema using DROP command.
The syntax of DROP command:
DROP SCHEMA schema_name RESTRICT; DROP Table table_name CASCADE;
Comparison Chart:
| 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 |
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