MySQL TRUNCATE() function

TRUNCATE() function

MySQL TRUNCATE() returns a number after truncated to certain decimal places. The number and the number of decimal places are specified as arguments of the TRUNCATE function.

• TRUNCATE is a fast and efficient way to remove all rows from a table compared to using DELETE with no WHERE clause.
• TRUNCATE is a non-logged operation, meaning it doesn't generate transaction logs for each deleted row.
• Since TRUNCATE is a non-logged operation and doesn't require as much resource overhead as a DELETE, it is significantly faster, especially for very large tables.
• TRUNCATE doesn't fire triggers associated with the table.
• When a table has an auto-incrementing primary key, using TRUNCATE resets the auto-increment counter to its starting value.
• Unlike dropping and re-creating a table, TRUNCATE preserves the table's structure, constraints, indexes, and other attributes.
• When a table is part of a foreign key relationship, using TRUNCATE might be more straightforward compared to using DELETE with cascading delete actions.

Syntax:

TRUNCATE(N, D);

Arguments:

Note: When the value of ‘D’ is 0 the results have no fractional part and the ‘D’ digits left of the decimal point of the value ‘N’ become 0 when the value of ‘D’ is negative.

Syntax Diagram:

MySQL Version: 8.0

Example of MySQL TRUNCATE() function

Code:

SELECT TRUNCATE(2.465,1);

Explanation:

The above MySQL statement will return a value truncating 2.465 up to 1 decimal place.

Output:

mysql> SELECT TRUNCATE(2.465,1);
+-------------------+
| TRUNCATE(2.465,1) |
+-------------------+
|               2.4 | 
+-------------------+
1 row in set (0.00 sec)

Example :TRUNCATE() function with negative decimal places

Code:

SELECT TRUNCATE(142.465,-2);

Explanation:

The above MySQL statement will return a value truncating 142.465 up to -2 decimal places.

Output:

mysql> SELECT TRUNCATE(142.465,-2);
+----------------------+
| TRUNCATE(142.465,-2) |
+----------------------+
|                  100 | 
+----------------------+
1 row in set (0.00 sec)

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