What are the commands to clear table data in SQL?

SQL There are two commands to clear table data: TRUNCATE TABLE and DELETE. TRUNCATE TABLE directly truncates the table, deletes all data but retains the structure, is fast, and cannot be rolled back; DELETE deletes data row by row, can filter deletion conditions, and can be rolled back but is slow.

SQL commands to clear table data

In SQL, there are two main commands that can be used to clear table data ：

• TRUNCATE TABLE
• DELETE

##TRUNCATE TABLE

TRUNCATE TABLE command is a quick and effective way to clear table data. It truncates the table directly, removing all rows and data but retaining the table structure and any constraints.

<code class="sql">TRUNCATE TABLE table_name;</code>

Benefits:

Very fast because it does not perform line-by-line deletion.
• Preserve the table structure.

Disadvantages:

Cannot be rolled back.
• If there are foreign key constraints, errors may occur.

DELETE

DELETE command deletes data in the table row by row. It accepts an optional WHERE clause that allows filtering rows to be deleted based on specific criteria.

<code class="sql">DELETE FROM table_name [WHERE condition];</code>

Benefits:

You can use the
• WHERE clause to filter the rows to be deleted.
Can be rolled back, provided that transactions are enabled.

Disadvantages:

is slower than
• TRUNCATE TABLE, especially when the table is large.
Logging overhead will be incurred.

Choose the appropriate command

The following factors should be considered when selecting the

TRUNCATE TABLE and DELETE commands :

##Performance:
• TRUNCATE TABLE is generally faster than DELETE.
Rollback:
• If you need to rollback a delete operation, you should use DELETE.
Foreign key constraints:
• TRUNCATE TABLE may conflict with foreign key constraints.
Filtering:
• If you need to delete rows based on conditions, you should use DELETE.

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