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:
| Name | Description |
|---|---|
| N | A number which is to be truncated up to D decimal places. |
| D | A number indicating up to how many decimal places, N is to be truncated. |
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)