The ROUND function in SQL Server is a powerful tool that allows you to round numeric values to a specific number of decimal places. This function is crucial for data manipulation and analysis, as it helps to standardize and simplify numerical data, making it easier to read and understand.

**Contents:**

- Syntax of the ROUND function
- Examples of the ROUND function
- Comparison with other rounding functions
- Common use cases and scenarios
- Tips and best practices
- Troubleshooting common errors
- Summary

## SQL ROUND function: Syntax

**ROUND** (numeric_expression, length [, function])

The function takes three parameters:

**Numeric expression:**The numeric value or column to be rounded**Length:**The number of decimal places to round the numeric expression to**Function (optional):**A value of 0 (default) rounds to the nearest value, while a value of 1 rounds towards zero (truncation)

## SQL ROUND function: Example

The SQL Server ROUND () Function has been designed by Microsoft and can be used in various fields, such as math, engineering, finance, etc. It does not have any limits on input values and always rounds up or down to the nearest whole number without fractions. The *default rounding direction* is **up** which means that it will *round numbers greater than 0 upwards*.

In fact, using it is quite simple. Let’s have a look at the below table:

ID | Planets | Radius | SunSeason |
---|---|---|---|

1 | Mars | 3396 | 687.58 |

2 | Saturn | 10759.22 | 10759.22 |

3 | Neptune | 24764 | 60190.91 |

4 | Mercury | 2439 | 115.18 |

5 | Venus | 6051 | 234.56 |

### Example #1: **Rounding with different length values**

Rounding the **‘Radius’** column to the nearest thousand:

**SELECT **ID, Planets, **ROUND**(Radius, -3) **AS** RoundedRadius, SunSeason
**FROM** PlanetaryData

Result:

ID | Planets | Radius | SunSeason |
---|---|---|---|

1 | Mars | 3000 | 687.58 |

2 | Saturn | 11000 | 10759.22 |

3 | Neptune | 25000 | 60190.91 |

4 | Mercury | 2000 | 115.18 |

5 | Venus | 6000 | 234.56 |

Rounding the **‘SunSeason’** column to one decimal place:

**SELECT **ID, Planets, Radius, **ROUND**(SunSeason, 1) **AS** RoundedSunSeason
**FROM** PlanetaryData

Result:

ID | Planets | Radius | SunSeason |
---|---|---|---|

1 | Mars | 3000 | 687.6 |

2 | Saturn | 11000 | 10759.2 |

3 | Neptune | 25000 | 60190.9 |

4 | Mercury | 2000 | 115.2 |

5 | Venus | 6000 | 234.6 |

### Example #2: **Rounding with the optional function parameter**

Truncating the **‘Radius’** column to the nearest hundred:

**SELECT** ID, Planets, **ROUND**(Radius, -2, 1) **AS** TruncatedRadius, SunSeason
**FROM** PlanetaryData

Result:

ID | Planets | Radius | SunSeason |
---|---|---|---|

1 | Mars | 3300 | 687.58 |

2 | Saturn | 10700 | 10759.22 |

3 | Neptune | 24700 | 60190.91 |

4 | Mercury | 2400 | 115.18 |

5 | Venus | 6000 | 234.56 |

Truncating the ‘SunSeason’ column to the nearest integer:

**SELECT** ID, Planets, Radius, **ROUND**(SunSeason, 0, 1) **AS** TruncatedSunSeason
**FROM** PlanetaryData

Result:

ID | Planets | Radius | SunSeason |
---|---|---|---|

1 | Mars | 3396 | 687 |

2 | Saturn | 10759.22 | 10759 |

3 | Neptune | 24764 | 60190 |

4 | Mercury | 2439 | 115 |

5 | Venus | 6051 | 234 |

**Alternatives to the ROUND function**

In SQL Server, there are several rounding functions available to achieve different types of rounding operations. In addition to the **ROUND** function, **FLOOR** and **CEILING** functions are commonly used to round numbers. Here’s a more detailed comparison of these functions:

**FLOOR function**

The FLOOR function in SQL Server rounds a given numeric expression down to the nearest integer value. Unlike ROUND, which rounds to the nearest whole number, FLOOR always rounds down, regardless of the decimal value.

Syntax:

**FLOOR**(numeric_expression)

Example using ‘PlanetaryData’ table:

**SELECT** ID, Planets, Radius, **FLOOR**(SunSeason) **AS** FlooredSunSeason
**FROM** PlanetaryData

Result:

ID | Planets | Radius | SunSeason |
---|---|---|---|

1 | Mars | 3396 | 687 |

2 | Saturn | 10759.22 | 10759 |

3 | Neptune | 24764 | 60190 |

4 | Mercury | 2439 | 115 |

5 | Venus | 6051 | 234 |

**CEILING function**

The CEILING function in SQL Server rounds a given numeric expression up to the nearest integer value. It is the counterpart of the FLOOR function, as it always rounds up, regardless of the decimal value.

Syntax:

**CEILING**(numeric_expression)

Example using ‘PlanetaryData’ table:

**SELECT** ID, Planets, Radius, **CEILING**(SunSeason) **AS** CeilingSunSeason
**FROM** PlanetaryData

Result:

ID | Planets | Radius | SunSeason |
---|---|---|---|

1 | Mars | 3396 | 688 |

2 | Saturn | 10759.22 | 10760 |

3 | Neptune | 24764 | 60191 |

4 | Mercury | 2439 | 116 |

5 | Venus | 6051 | 235 |

**Comparison of the ROUND, FLOOR and CEILING functions**

While the ROUND function allows for more versatile rounding, including the ability to round to a specific decimal place and truncate decimal values, the FLOOR and CEILING functions are useful in specific scenarios where you need to round a number down or up to the nearest integer.

For example, FLOOR can be used to determine the maximum number of whole units that can be produced given a certain amount of raw material, while CEILING can be utilized to calculate the minimum number of whole units needed to fulfill a certain demand.

In summary, understanding the differences between the ROUND, FLOOR, and CEILING functions and their respective use cases will enable you to choose the most suitable function for your specific data manipulation and analysis needs.

**ROUND function: Common use cases and scenarios**

The ROUND function in SQL Server is widely used in various data manipulation and analysis scenarios to ensure consistent and readable results. Here are some common use cases where rounding is essential:

### Case #1: **Rounding currency values**

When dealing with financial data, it is essential to round currency values to two decimal places, representing cents or the smallest unit of currency. This ensures accurate and consistent reporting and avoids potential discrepancies due to floating-point arithmetic.

Let’s create a ‘SalesData’ test table with some sample data:

**CREATE TABLE** SalesData
(
OrderID INT,
ProductID INT,
SalePrice DECIMAL(10, 4),
Discount DECIMAL(10, 4)
)
**INSERT INTO** SalesData (OrderID, ProductID, SalePrice, Discount)
**VALUES** (1, 101, 49.9912, 0.1023),
(2, 102, 29.8990, 0.0540),
(3, 103, 19.4999, 0.1500),
(4, 104, 99.0012, 0.2500),
(5, 105, 59.9000, 0.3000)

Now, let’s use the ROUND function to round the **‘SalePrice’** and **‘Discount’** columns to two decimal places:

**SELECT** OrderID, ProductID, **ROUND**(SalePrice, 2) **AS** RoundedSalePrice, **ROUND**(Discount, 2) **AS** RoundedDiscount
**FROM** SalesData

Result:

OrderID | ProductID | RoundedSalePrice | RoundedDiscount |
---|---|---|---|

1 | 101 | 49.99 | 0.10 |

2 | 102 | 29.90 | 0.05 |

3 | 103 | 19.50 | 0.15 |

4 | 104 | 99.00 | 0.25 |

5 | 105 | 59.90 | 0.30 |

As you can see, the ROUND function has successfully rounded the ‘SalePrice’ and ‘Discount’ columns to two decimal places, ensuring consistent and accurate representation of the financial data.

### Case #2: **Rounding percentages**

Percentages are often used in reporting and data analysis to represent proportions or ratios. To maintain consistency and readability, percentages can be rounded to a specific decimal place, such as one or two decimal places.

Let’s create an ‘EmployeePerformance’ test table with some sample data:

**CREATE TABLE** EmployeePerformance
(
EmployeeID INT,
TasksCompleted INT,
TotalTasks INT
)
**INSERT INTO** EmployeePerformance (EmployeeID, TasksCompleted, TotalTasks)
**VALUES** (1, 45, 50),
(2, 32, 40),
(3, 38, 40),
(4, 25, 30),
(5, 22, 25)

Now, let’s use the ROUND function to calculate the task completion percentage for each employee, rounded to one decimal place:

**SELECT** EmployeeID, **ROUND**((TasksCompleted * 100.0) / TotalTasks, 1) **AS** CompletionPercentage
**FROM** EmployeePerformance

Result:

EmployeeID | CompletionPercentage |
---|---|

1 | 90.0 |

2 | 80.0 |

3 | 95.0 |

4 | 83.3 |

5 | 88.0 |

As you can see, the ROUND function has successfully calculated the task completion percentage for each employee and rounded the result to one decimal place, providing a clear and concise representation of the employee performance data.

### Case #3: **Rounding large datasets for better readability**

When working with large datasets containing numerical values, rounding can significantly improve the overall presentation and readability of the data. By rounding values to a suitable decimal place or whole number, you can make the data more comprehensible and easier to analyze.

Let’s create a ‘PopulationStatistics’ test table with some sample data:

**CREATE TABLE** PopulationStatistics
(
Country NVARCHAR(50),
Date DATE,
Population BIGINT,
GrowthRate DECIMAL(10, 4)
)
**INSERT INTO** PopulationStatistics (Country, Date, Population, GrowthRate)
**VALUES** ('United States', '2023-01-01', 334780000, 0.7123),
('China', '2023-01-01', 1439323776, 0.5400),
('India', '2023-01-01', 1393409038, 1.0212),
('Brazil', '2023-01-01', 213850000, 0.7500),
('Germany', '2023-01-01', 83200000, 0.2100)

Now, let’s use the ROUND function to round the **‘Population’** column to millions and the **‘GrowthRate’** column to two decimal places:

**SELECT** Country, YEAR(Date) **AS** Year, **ROUND**(Population / 1000000.0, 2) **AS** PopulationInMillions, **ROUND**(GrowthRate, 2) **AS** RoundedGrowthRate
**FROM** PopulationStatistics

Result:

Country | Year | PopulationInMillions | RoundedGrowthRate |
---|---|---|---|

United States | 2023 | 334.78 | 0.71 |

China | 2023 | 1439.32 | 0.54 |

India | 2023 | 1393.41 | 1.02 |

Brazil | 2023 | 213.85 | 0.75 |

Germany | 2023 | 83.20 | 0.21 |

As you can see, the ROUND function has successfully rounded the ‘Population’ column to millions and the ‘GrowthRate’ column to two decimal places, providing a more readable and comprehensible representation of the population statistics data.

### Case #4: **Rounding for aggregation and statistical analysis**

Rounding can also play a crucial role when aggregating data or performing statistical analysis. By rounding values to a specific decimal place, you can ensure that the aggregated data remains consistent and comparable.

Let’s create a ‘ProductRatings’ test table with some sample data:

**CREATE TABLE** ProductRatings
(
RatingID INT,
ProductID INT,
Rating DECIMAL(10, 2)
)
**INSERT INTO** ProductRatings (RatingID, ProductID, Rating)
**VALUES** (1, 101, 4.5),
(2, 101, 5.0),
(3, 101, 4.2),
(4, 102, 3.8),
(5, 102, 4.5),
(6, 103, 5.0),
(7, 103, 4.7),
(8, 104, 3.5),
(9, 104, 2.8),
(10, 105, 4.0)

Now, let’s use the ROUND function to calculate the average rating for each product, rounded to one decimal place:

**SELECT** ProductID, COUNT(*) **AS** NumberOfRatings, **ROUND**(AVG(Rating), 1) **AS** AverageRating
**FROM** ProductRatings
**GROUP BY** ProductID

Result:

ProductID | NumberOfRatings | AverageRating |
---|---|---|

101 | 3 | 4.6 |

102 | 2 | 4.2 |

103 | 2 | 4.9 |

104 | 2 | 3.2 |

105 | 1 | 4.0 |

As you can see, the ROUND function has successfully calculated the average rating for each product and rounded the result to one decimal place, providing a clear and concise representation of the product ratings data.

**ROUND function: Tips and best practices**

Consider the following guidelines and best practices when working with the ROUND function in SQL Server to maximize efficiency, preserve accuracy, and assure consistent results:

**Choose the proper rounding function**

You may need to utilize the ROUND, FLOOR, or CEILING functions to obtain the correct rounding behavior, depending on your individual use case. Knowing the distinctions between these routines will allow you to select the most appropriate one for your data processing and analysis requirements.

**Be cognizant of data kinds**

ROUND returns a rounded value of the same data type as the input value. To ensure proper rounding behavior and avoid unexpected results while working with integers, it may be necessary to cast them to a floating-point type.

Example:

**SELECT** **ROUND**(CAST(1234 AS DECIMAL(10, 2)), 1) **AS** RoundedValue

**Avoid rounding errors**

Due to the nature of floating-point arithmetic, rounding mistakes can occur while working with floating-point numbers. To reduce the impact of rounding mistakes on your calculations, consider rounding only when necessary and storing accurate numbers using appropriate data types, such as DECIMAL.

**Use the proper rounding granularity**

To retain the intended level of precision and readability when rounding values, it is essential to select the proper granularity, such as the number of decimal places. Overly aggressive rounding can lead to the loss of valuable data, while insufficient rounding can result in data that is cluttered and difficult to understand.

**Check your rounding reasoning**

While creating rounding logic, ensure that it operates as expected by testing it with a variety of input values and scenarios. Little differences can have a huge impact on the final outcome when working with enormous datasets.

**Be mindful of negative values**

Remember that when rounding negative integers with the ROUND function, SQL Server rounds away from zero. This indicates that rounding a negative number with a decimal portion greater than or equal to 0.5 will result in a more negative number. Ensure that your rounding logic takes this behavior into account when dealing with negative values.

By adhering to these guidelines and recommendations, you can ensure that your usage of the ROUND function in SQL Server is effective, accurate, and consistent, resulting in improved data manipulation and analysis.

**ROUND function: Troubleshooting common errors**

When working with the ROUND function in SQL Server, you may encounter some common errors or issues. Here are a few of them and their respective solutions:

**Implicit conversion issues**

If you try to use the ROUND function with different data types for the input value and length, you may encounter an error due to an implicit conversion. To resolve this, ensure that you cast or convert the input value to the appropriate data type.

Example:

*-- This will cause an error*
SELECT **ROUND**(1234, 1.5)
*-- Solution: Convert the length to an integer*
SELECT **ROUND**(1234, CAST(1.5 **AS** INT))

**Division by zero errors**

When using the ROUND function in conjunction with division operations, you may encounter a division by zero error. To avoid this issue, make sure to check for zero values before performing the division.

Example:

*-- This will cause a division by zero error if 'TotalTasks' is zero*
SELECT **ROUND**((TasksCompleted * 100.0) / TotalTasks, 1) **AS** CompletionPercentage
**FROM** EmployeePerformance
*-- Solution: Use ***NULLIF** to handle zero values
SELECT **ROUND**((TasksCompleted * 100.0) / **NULLIF**(TotalTasks, 0), 1) **AS** CompletionPercentage
**FROM** EmployeePerformance

**Inaccurate results with FLOAT data type**

The FLOAT data type can cause inaccurate results due to its approximate nature. If you notice inconsistencies in your rounding results, consider using the DECIMAL data type instead, which provides greater precision and accuracy.

Example:

*-- This might cause inaccurate results*
SELECT **ROUND**(1234.5678, 2) **AS** RoundedValue
**FROM** MyTable
*-- Solution: Use the ***DECIMAL** data type
SELECT **ROUND**(CAST(1234.5678 **AS** **DECIMAL**(10, 4)), 2) **AS** RoundedValue
**FROM** MyTable

**Incorrect rounding behavior**

If you observe unexpected rounding results, it might be due to an issue with data types or rounding direction. Make sure to cast the input value to the correct data type, and be aware of the rounding direction for positive and negative values.

Consider the following example where you are trying to round a negative value and expect it to be rounded towards zero. However, the ROUND function in SQL Server rounds away from zero, which might lead to unexpected results.

Example:

*-- Create a test table with negative values*
**CREATE TABLE** TestTable
(
ValueID INT,
Value DECIMAL(10, 2)
)
**INSERT INTO** TestTable (ValueID, Value)
**VALUES** (1, -7.45),
(2, -4.26),
(3, -1.75)
*-- Use the ***ROUND** function to round the values
**SELECT** ValueID, **ROUND**(Value, 0) **AS** RoundedValue
**FROM** TestTable

Result:

ValueID | RoundedValue |
---|---|

1 | -7 |

2 | -4 |

3 | -2 |

In this example, you might have expected the value -1.75 to be rounded to -1 (towards zero). However, because SQL Server’s ROUND function rounds away from zero, it was rounded to -2.

**Solution:**

To round towards zero, you can use the following logic:

**SELECT** ValueID,
CASE
WHEN Value < 0 THEN **CEILING**(Value)
ELSE FLOOR(Value)
END **AS** RoundedValue
**FROM** TestTable

Result:

ValueID | RoundedValue |
---|---|

1 | -7 |

2 | -4 |

3 | -1 |

By understanding these common errors and their solutions, you can effectively troubleshoot issues related to the ROUND function in SQL Server and ensure accurate and consistent results in your data manipulation and analysis tasks.

## Summary

This article provides a comprehensive overview of the SQL Server ROUND function and its various applications. We have covered the syntax, rounding behavior, and how to utilize the ROUND function in various contexts, as well as a comparison to other rounding functions, typical use cases, best practices, and more.

By comprehending the complexities of the ROUND function and using the techniques and best practices discussed in this article, you will be able to alter and analyze your data in SQL Server with precision and consistency.

You can use dbForge Studio for SQL Server to put these ideas into effect and experiment with all the examples provided in the article. It is a robust integrated development environment (IDE) that provides a complete set of tools for managing and optimizing SQL Server databases, developing and debugging T-SQL scripts, and analyzing and visualizing data.

Mastering the ROUND function and its different applications will allow you to work with numerical data in SQL Server more efficiently. With dbForge Studio for SQL Server, you can easily implement the principles covered in this tutorial and strengthen your SQL Server development and administration skills.

Tags: sql round, statements Last modified: March 31, 2023