ROUND (Transact-SQL)

ROUND (Transact-SQL)

 

THIS TOPIC APPLIES TO: yesSQL Server (starting with 2008)yesAzure SQL DatabaseyesAzure SQL Data Warehouse yesParallel Data Warehouse

Returns a numeric value, rounded to the specified length or precision.

Topic link icon Transact-SQL Syntax Conventions

-- Syntax for SQL Server and Azure SQL Database  
  
ROUND ( numeric_expression , length [ ,function ] )  

-- Syntax for Azure SQL Data Warehouse and Parallel Data Warehouse  
  
ROUND (numeric_expression , length )  

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.

Returns the following data types.

Expression resultReturn type
tinyintint
smallintint
intint
bigintbigint
decimal and numeric category (p, s)decimal(p, s)
money and smallmoney categorymoney
float and real categoryfloat

ROUND always returns a value. If length is negative and larger than the number of digits before the decimal point, ROUND returns 0.

ExampleResult
ROUND(748.58, -4)0

ROUND returns a rounded numeric_expression, regardless of data type, when length is a negative number.

ExamplesResult
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

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)  

D. Using ROUND and estimates

The following example shows two expressions that demonstrate by using ROUND the last digit is always an estimate.

SELECT ROUND(123.994999, 3), ROUND(123.995444, 3);  

Here is the result set.

-------- ---------

123.995000 123.995444

E. Using ROUND and rounding approximations

The following example shows rounding and approximations.

SELECT ROUND(123.4545, 2), ROUND(123.45, -2);  

Here is the result set.

-------- ----------

123.45 100.00

CEILING (Transact-SQL)
Data Types (Transact-SQL)
Expressions (Transact-SQL)
FLOOR (Transact-SQL)
Mathematical Functions (Transact-SQL)

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