ROUND (Transact-SQL)
Returns a numeric value, rounded to the specified length or precision.
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Transact-SQL Syntax Conventions
Syntax
ROUND ( numeric_expression , length [ ,function ] )
Arguments
numeric_expression
Is an expression of the exact numeric or approximate numeric data type category, except for the bit data type.length
Is the precision to which numeric_expression is to be rounded. length must be an expression of type tinyint, smallint, or int. When length is a positive number, numeric_expression is rounded to the number of decimal positions specified by length. When length is a negative number, numeric_expression is rounded on the left side of the decimal point, as specified by length.function
Is the type of operation to perform. function must be tinyint, smallint, or int. When function is omitted or has a value of 0 (default), numeric_expression is rounded. When a value other than 0 is specified, numeric_expression is truncated.
Return Types
Returns the following data types.
Expression result |
Return type |
|---|---|
tinyint |
int |
smallint |
int |
int |
int |
bigint |
bigint |
decimal and numeric category (p, s) |
decimal(p, s) |
money and smallmoney category |
money |
float and real category |
float |
Remarks
ROUND always returns a value. If length is negative and larger than the number of digits before the decimal point, ROUND returns 0.
Example |
Result |
|---|---|
ROUND(748.58, -4) |
0 |
ROUND returns a rounded numeric_expression, regardless of data type, when length is a negative number.
Examples |
Result |
|---|---|
ROUND(748.58, -1) |
750.00 |
ROUND(748.58, -2) |
700.00 |
ROUND(748.58, -3) |
Results in an arithmetic overflow, because 748.58 defaults to decimal(5,2), which cannot return 1000.00. |
To round up to 4 digits, change the data type of the input. For example: SELECT ROUND(CAST (748.58 AS decimal (6,2)),-3); |
1000.00 |
Examples
A. Using ROUND and estimates
The following example shows two expressions that demonstrate by using ROUND the last digit is always an estimate.
SELECT ROUND(123.9994, 3), ROUND(123.9995, 3)
GO
Here is the result set.
----------- -----------
123.9990 124.0000
B. Using ROUND and rounding approximations
The following example shows rounding and approximations.
SELECT ROUND(123.4545, 2);
GO
SELECT ROUND(123.45, -2);
GO
Here is the result set.
----------
123.4500
(1 row(s) affected)
--------
100.00
(1 row(s) affected)
C. Using ROUND to truncate
The following example uses two SELECT statements to demonstrate the difference between rounding and truncation. The first statement rounds the result. The second statement truncates the result.
SELECT ROUND(150.75, 0);
GO
SELECT ROUND(150.75, 0, 1);
GO
Here is the result set.
--------
151.00
(1 row(s) affected)
--------
150.00
(1 row(s) affected)