What does drop mean in SQL?

What is DROP keyword?

DROP is a keyword in SQL which removes or deletes an element specified in the rest of the SQL statement.

What is the difference between DROP and TRUNCATE?

1. The DROP command is used to remove table definition and its contents. Whereas the TRUNCATE command is used to delete all the rows from the table.

What does DROP do in database?

Dropping a database deletes the database from an instance of SQL Server and deletes the physical disk files used by the database. If the database or any one of its files is offline when it is dropped, the disk files are not deleted. These files can be deleted manually by using Windows Explorer.

What is delete and DROP in SQL?

DELETE is a Data Manipulation Language command, DML command and is used to remove tuples/records from a relation/table. Whereas DROP is a Data Definition Language, DDL command and is used to remove named elements of schema like relations/table, constraints or entire schema. … DROP is DDL.

IT IS INTERESTING:  Is node js built on C?


DROP and TRUNCATE are DDL commands, whereas DELETE is a DML command. DELETE operations can be rolled back (undone), while DROP and TRUNCATE operations cannot be rolled back.

Is TRUNCATE faster than delete?

TRUNCATE is faster than DELETE , as it doesn’t scan every record before removing it. TRUNCATE TABLE locks the whole table to remove data from a table; thus, this command also uses less transaction space than DELETE .

Why use TRUNCATE instead of delete?

Truncate removes all records and doesn’t fire triggers. Truncate is faster compared to delete as it makes less use of the transaction log. Truncate is not possible when a table is referenced by a Foreign Key or tables are used in replication or with indexed views.

How do I drop if a database exists?

The DROP DATABASE statement allows you to delete one or more databases with the following syntax:

  1. DROP DATABASE [ IF EXISTS ] database_name [,database_name2,… ];
  2. Cannot drop database “database_name” because it is currently in use. Code language: PHP (php)

Can we drop a table or column which has primary key?

We can remove PRIMARY KEY constraint from a column of an existing table by using DROP keyword along with ALTER TABLE statement.

What is the difference between drop table and drop database?

Answer: DROP DATABASE drops all tables in the database and deletes the database. … … The drop table command is used to delete a table and all rows in the table. … Deleting all of the records in the table leaves the table including column and constraint information.

IT IS INTERESTING:  Question: Can we alter primary key in SQL Server?

Is update a DDL command?

DDL is Data Definition Language which is used to define data structures.

Difference between DDL and DML:

Basic command present in DDL are CREATE, DROP, RENAME, ALTER etc. BASIC command present in DML are UPDATE, INSERT, MERGE etc.

What is the use of DROP in SQL?

DROP is used to delete a whole database or just a table. The DROP statement destroys the objects like an existing database, table, index, or view. A DROP statement in SQL removes a component from a relational database management system (RDBMS).

Is alter a DDL command?

Basically, any CREATE/DROP/ALTER command is DDL. DML – alter the information/data within the schema; without updating the schema. This includes DELETE and UPDATE statements.

Categories JS