What is the Difference Between delete and truncate

The main difference between delete and truncate is that the delete removes single, multiple or all the records from the table while the truncate removes all the records as well as the structure of the table from the database.  

A database is a collection of related data. Database Management System (DBMS) allows to create and manage data in databases. Moreover, a DBMS that follows the relational model is a Relational Database Management System (RDBMS). It stores data in tables, and the tables are related to each other. The Structured Query Language (SQL) allows the user to write queries to manipulate data in the tables. There are various SQL commands, and two of them are delete and truncate.

Key Areas Covered

1. What is delete
     – Definition, Functionality
2. What is truncate
     – Definition, Functionality
3. What is the Difference Between delete and truncate
    – Comparison of Key Differences

Key Terms

DBMS, delete, RDBMS, truncate

What is delete

The delete command helps to remove the records from a table in the database. Refer below table called student.

The SQL statement as all the records from the table student follows delete.

 delete from student;

It is also possible to delete a specific record from the table.

delete from student where id =2;

Here, this SQL statement will delete the record that has the id 2. After executing this statement, there will be two records in the table: records with id 1 and 3.

What is Truncate

The truncate command helps to remove all the records from a table. It also removes the table structure from the database. Therefore, when executing the truncate command on a specific table, it also initializes the primary key.

The following SQL command deletes all the records from the student table. Moreover, it removes the table structure from the database.

truncate table student;

Difference Between Delete and Truncate

Definition

delete is a DML command that removes one or more records from a table in a database whereas truncate is a DDL command that marks the extents of a table for deallocation. Thus, this is the fundamental difference between delete and truncate.

Functionality

The main difference between delete and truncate is that while delete command removes a single, multiple or all records from the table according to the specified SQL statement, truncate command removes all the records and the table structure from the database.

Table Structure

Furthermore, another difference between delete and truncate is that the delete command does not affect the table structure while the truncate command eliminates the table structure from the database.

Command Type

Command type is also a difference between delete and truncate. While delete is a Data Manipulation Language (DML) command, truncate is a Data Definition Language (DDL) command.

where Clause

Moreover, it is possible to use where clause with the delete command to filter and remove records. However, it is not possible to use where clause with truncate command.

Execution Speed

Execution speed is another difference between delete and truncate. As delete command maintains a log, it is slow. However, as truncate command maintains minimal logging in transaction log, it executes faster.

Association with Index Views

Furthermore, it is possible to use the delete command with indexed views, but it is not possible to use the truncate command with indexed views.

Required Transaction Space

Besides, delete command uses more transaction space than truncate command. Hence, this is another difference between delete and truncate.

Conclusion

In brief, delete and truncate are two SQL commands. But, the main difference between delete and truncate is that the delete removes single, multiple or all the records from the table while the truncate removes all the records as well as the structure of the table from the database. 

Reference:

1. “Using DELETE SQL Command.” Types of Network Topology in Computer Networks | Studytonight, Available here.
2. “Truncate, Drop or Rename a Table.” Types of Network Topology in Computer Networks | Studytonight, Available here.

Image Courtesy:

1. “2394312” (CC0) via Pixabay

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