What is the difference between DROP and TRUNCATE?

In SQL, the DROP command is used to remove the whole database or table indexes, data, and more. Whereas the TRUNCATE command is used to remove all the rows from the table.

What is the difference between DROP DELETE and TRUNCATE?

Unlike TRUNCATE which only deletes the data of the tables, the DROP command deletes the data of the table as well as removes the entire schema/structure of the table from the database.

What are 2 differences between DELETE and TRUNCATE?

Delete and truncate both commands can be used to delete data of the table. Delete is a DML command whereas truncate is DDL command. Truncate can be used to delete the entire data of the table without maintaining the integrity of the table. On the other hand , delete statement can be used for deleting the specific data.

Which is better TRUNCATE or DROP?

Performance-wise the DROP command is quick to perform but slower than TRUNCATE because it gives rise to complications. Unlike DELETE we can't rollback the data after using the DROP command. In the DROP command, table space is freed from memory because it permanently delete table as well as all its contents.

What is the difference between DROP and DELETE?

DELETE command is a Data Manipulation Language command whereas, DROP is a Data Definition Language Command. The point that distinguishes DELETE and DROP command is that DELETE is used to remove tuples from a table and DROP is used to remove entire schema, table, domain or constraints from the database.

Difference between DELETE, TRUNCATE AND DROP in SQL.

What is difference between TRUNCATE and DROP TABLE?

In SQL, the DROP command is used to remove the whole database or table indexes, data, and more. Whereas the TRUNCATE command is used to remove all the rows from the table.

Is TRUNCATE a DDL or DML?

Although TRUNCATE TABLE is similar to DELETE , it is classified as a DDL statement rather than a DML statement. It differs from DELETE in the following ways: Truncate operations drop and re-create the table, which is much faster than deleting rows one by one, particularly for large tables.

Can we rollback TRUNCATE?

You cannot ROLLBACK TRUNCATE

Simply, you cannot rollback a transaction if it is already committed but you can do something else to get the data back (or at least some parts of it). When you execute the TRUNCATE statement, your data is still in the MDF file.

Why TRUNCATE is faster?

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 . Unlike DELETE , TRUNCATE does not return the number of rows deleted from the table.

What is the difference between union and union all?

The UNION ALL command is equal to the UNION command, except that UNION ALL selects all values. The difference between Union and Union all is that Union all will not eliminate duplicate rows, instead it just pulls all rows from all tables fitting your query specifics and combines them into a table.

What is DML DDL and DCL?

These SQL commands are mainly categorized into four categories as: DDL – Data Definition Language. DQl – Data Query Language. DML – Data Manipulation Language. DCL – Data Control Language.

What is the difference between DDL and DML commands in SQL?

DDL is Data Definition Language which is used to define data structures. For example: create table, alter table are instructions in SQL. DML: DML is Data Manipulation Language which is used to manipulate data itself.

What is DML and DDL?

DDL stands for Data Definition Language. DML stands for Data Manipulation Language. 2. Usage. DDL statements are used to create database, schema, constraints, users, tables etc.

Can we rollback after DROP TABLE?

You cannot roll back a DROP TABLE statement. Note: For an external table, this statement removes only the table metadata in the database.

What is the difference between DROP TRUNCATE and delete command this question is required *?

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.

Does TRUNCATE free space?

Truncating a table does not give any free space back to the disk - you need to run a SHRINKDATABASE operation for the allocated space to be successfully de-allocated and returned to the disk.

What is rollback in SQL?

In SQL, ROLLBACK is a command that causes all data changes since the last BEGIN WORK , or START TRANSACTION to be discarded by the relational database management systems (RDBMS), so that the state of the data is "rolled back" to the way it was before those changes were made.

Does TRUNCATE remove indexes?

The truncate command only removes all rows of a table. It does not remove the columns, indexes, constraints, and schema.

Do we need commit after TRUNCATE?

TRUNCATE is a DDL command so it doesn't need an explicit commit because calling it executes an implicit commit. From a system design perspective a transaction is a business unit of work. It might consist of a single DML statement or several of them. It doesn't matter: only full transactions require COMMIT.

Can we rollback after commit?

After you commit the transaction, the changes are visible to other users' statements that execute after the commit. You can roll back (undo) any changes made during the transaction with the ROLLBACK statement (see ROLLBACK.

What are cursors in SQL?

A cursor holds the rows (one or more) returned by a SQL statement. The set of rows the cursor holds is referred to as the active set. You can name a cursor so that it could be referred to in a program to fetch and process the rows returned by the SQL statement, one at a time.

Is TRUNCATE transactional?

In Oracle, TRUNCATE TABLE is a DDL statement that cannot be used in a transaction (or, more accurately, cannot be rolled back).

What is DROP in DDL?

The DROP command is a type of SQL DDL command, that is used to delete an existing database or an object within a database.

Why delete is DML?

DELETE is a DML(Data Manipulation Language) command and is used when we specify the row(tuple) that we want to remove or delete from the table or relation.

Is rename a DDL command?

DDL commands are Create, Alter, Drop, Rename, Truncate, Comment.