trunc

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Truncates the fractional part of a number toward zero.

Syntax

trunc(<expr>)

Arguments

ArgumentTypeDescription
<expr>floatInput value.

Returns

Returns float. Returns NULL if the input is NULL.

Usage notes

For an int or uint column, cast the value to float before calling this function.

Examples

Discard fractional units from signed measurements. Compare truncation with floor when corrections can be negative.

VALUES ('received', 12.8), ('returned', -12.8)
SELECT $0 AS movement, $1 AS measured_units
SELECT
    movement,
    measured_units,
    trunc(measured_units) AS truncated_units,
    floor(measured_units) AS floor_units
+----------+----------------+-----------------+-------------+
| movement | measured_units | truncated_units | floor_units |
+----------+----------------+-----------------+-------------+
| received | 12.8           | 12.0            | 12.0        |
| returned | -12.8          | -12.0           | -13.0       |
+----------+----------------+-----------------+-------------+

Truncation moves toward zero; floor moves toward negative infinity. They differ for the returned quantity.