TRUNC function
The TRUNC function truncates numbers to the previous integer or decimal.
The TRUNC function can optionally include a second argument as an INTEGER
to indicate
the number of decimal places for rounding, in either direction. When you don't
provide the second argument, the function rounds to the nearest whole number. When the
second argument integer is specified, the function rounds to the nearest
number with integer decimal places of precision.
This function can also truncate a TIMESTAMP
and return a DATE
. For more information, see TRUNC function.
Syntax
TRUNC(number [ , integer ])
Arguments
 number

A number or an expression that evaluates to a number. It can be the
DECIMAL
,FLOAT8
orSUPER
type. Amazon Redshift can convert other data types per the implicit conversion rules.  integer

(Optional) An
INTEGER
that indicates the number of decimal places of precision, in either direction. If no integer is provided, the number is truncated as a whole number; if an integer is specified, the number is truncated to the specified decimal place. This isn't supported for theSUPER
data type.
Return type
TRUNC returns the same data type as the input number.
When the input is of the SUPER
type, the output retains the same dynamic type as the input while the static type remains the SUPER
type. When the dynamic type of SUPER
isn't a number, Amazon Redshift returns NULL
.
Examples
Some of the following examples use the TICKIT sample database. For more information, see Sample database.
To truncate the commission paid for a given sales transaction, use the following example.
SELECT commission, TRUNC(commission) FROM sales WHERE salesid=784;
+++  commission  trunc  +++  111.15  111  +++
To truncate the same commission value to the first decimal place, use the following example.
SELECT commission, TRUNC(commission,1) FROM sales WHERE salesid=784;
+++  commission  trunc  +++  111.15  111.1  +++
To truncate the commission with a negative value for the second argument, use the following example.
Note that 111.15
is rounded down to 110
.
SELECT commission, TRUNC(commission,1) FROM sales WHERE salesid=784;
+++  commission  trunc  +++  111.15  110  +++