Difference between Truncate and Delete in SQL Server

Question

What is the difference between Truncate and Delete in SQL Server

Nidhi Kumari · Answer

Difference Between TRUNCATE and DELETE in SQL Server Aspect TRUNCATE DELETE Operation Type DDL (Data Definition Language) DML (Data Manipulation Language) Purpose Removes all rows from a table quickly. Deletes specific rows or all rows based on a WHERE condition. Condition Support Does not support WHERE clause. Supports WHERE clause to filter rows for deletion. Performance Faster because it doesn't log individual row deletions. Slower as each row deletion is logged in the transaction log. Logging Minimal logging for performance; logs table structure changes. Fully logs each row deletion for rollback. Triggers Does not activate triggers. Activates triggers if defined on the table. Identity Reset Resets the identity column to its seed value. Does not reset the identity column. Rollback Can be rolled back if inside a transaction. Can be rolled back if inside a transaction. Table Locking Acquires a schema modification lock (locks entire table). Acquires row-level locks if WHERE is used; otherwise locks table. Usage Scenario Best for clearing all data from a table quickly. Used when specific rows need to be deleted. Key Points: Use TRUNCATE when you want to quickly remove all rows and reset the table to its initial state. Use DELETE when you need control over which rows are removed.

Tuhin Paul · Answer

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Shubham Sidnale · Answer

The TRUNCATE and DELETE commands in SQL Server are both used to remove data from a table but they have key differences in terms of functionality performance and how they affect the database. Key Differences Between TRUNCATE and DELETE Aspect TRUNCATE DELETE Type of Command DDL (Data Definition Language) DML (Data Manipulation Language) Usage Removes all rows from a table. Removes specific rows based on a condition or all rows if no condition is given. WHERE Clause Not allowed (removes all rows). Allowed (can delete specific rows). Logging Minimal logging for performance. Fully logged each deleted row is logged. Performance Faster due to minimal logging and no row-by-row operations. Slower due to row-by-row operations and full logging. Impact on Table Schema Resets identity columns (if any) to their seed value. Does not reset identity columns. Triggers Does not fire triggers. Fires triggers associated with DELETE. Rollback Support Can be rolled back if within a transaction. Can be rolled back if within a transaction. Foreign Key Constraints Cannot truncate a table with foreign key constraints. Can delete rows from a table with foreign key constraints if the constraints are satisfied. When to Use TRUNCATE When you need to quickly remove all data from a table. When you do not need to trigger DELETE triggers. When you want to reset identity columns. When to Use DELETE When you need to remove specific rows using a condition (e.g. DELETE FROM Employees WHERE Age > 50). When DELETE triggers are required. When the table is referenced by foreign key constraints and you must carefully manage data removal. Example Scenarios TRUNCATE Example -- Removes all rows from the 'Orders' table and resets any identity column TRUNCATE TABLE Orders; DELETE Example -- Deletes only rows where the order status is 'Completed' DELETE FROM Orders WHERE Status = 'Completed'; Conclusion Use TRUNCATE when you want to remove all data quickly and efficiently and table constraints allow it. Use DELETE when you need granular control over which rows to remove or when working with foreign key constraints and triggers.

Rajanikant Hawaldar · Answer

https://www.c-sharpcorner.com/blogs/difference-between-truncate-delete-and-drop-in-sql-server1

Ananthakrishna V · Answer

TRUNCATE removes all rows from a table without using a WHERE clause. DELETE can remove specific rows using a WHERE clause. DELETE activates triggers; TRUNCATE does not.

Vijay Pratap Singh · Answer

TRUNCATE : Use when you want to quickly remove all rows from a table and reset the identity values and you do not need to selectively delete rows or maintain a detailed transaction log. DELETE : Use when you need to selectively remove rows using conditions or when dealing with tables that have foreign key constraints. -- Create a table for demonstration CREATE TABLE Employees ( ID INT IDENTITY(11) Name NVARCHAR(50) ); -- Insert some data INSERT INTO Employees (Name) VALUES ('Alice') ('Bob') ('Charlie'); -- View data SELECT * FROM Employees; -- Truncate the table TRUNCATE TABLE Employees; -- Check the table (should be empty) SELECT * FROM Employees; -- Note: The identity column is reset INSERT INTO Employees (Name) VALUES ('David'); SELECT * FROM Employees; -- ID starts from 1 again DELETE -- Create a table for demonstration CREATE TABLE Employees ( ID INT IDENTITY(11) Name NVARCHAR(50) ); -- Insert some data INSERT INTO Employees (Name) VALUES ('Alice') ('Bob') ('Charlie'); -- View data SELECT * FROM Employees; -- Delete a specific row DELETE FROM Employees WHERE Name = 'Bob'; -- Check remaining rows SELECT * FROM Employees; -- Delete all rows (without resetting identity) DELETE FROM Employees; -- Insert new data INSERT INTO Employees (Name) VALUES ('Eve'); SELECT * FROM Employees; -- ID does not reset; starts after the last identity value Hope this will help

Rakesh Kamath · Answer

The TRUNCATE and DELETE commands in SQL Server are both used to remove data from a table but they have significant differences in their functionality performance and impact on the database. Here's a comparison: 1. Operation Scope TRUNCATE : Removes all rows from a table. It operates on the entire table and cannot include a WHERE clause. DELETE : Removes specific rows from a table. It allows the use of a WHERE clause to specify which rows to delete. 2. Performance TRUNCATE : Faster because it does not log individual row deletions in the transaction log. It deallocates the data pages used by the table instead of deleting rows one by one. DELETE : Slower because it logs each deleted row in the transaction log. It processes row-by-row deletions which can be time-consuming for large datasets. 3. Impact on Table Structure TRUNCATE : Resets the table’s identity column (if present) to its seed value. Cannot be used if the table is referenced by a foreign key constraint. DELETE : Does not reset the table’s identity column. Can delete rows even if the table is referenced by a foreign key but referential integrity constraints must be satisfied.