Επεξεργασία

Κοινή χρήση μέσω

ROUND (Transact-SQL)

  • Άρθρο

Applies to: SQL Server Azure SQL Database Azure SQL Managed Instance Azure Synapse Analytics Analytics Platform System (PDW) SQL analytics endpoint in Microsoft Fabric Warehouse in Microsoft Fabric

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

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.

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's 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), ROUND(123.45, -2);

Here's the result set.

----------  ----------
123.4500    100.00

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's the result set.

--------  
151.00  
  
(1 row(s) affected)  
  
--------  
150.00  
  
(1 row(s) affected)

See Also

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