The Decimal Datatype in SQL Server

Welcome Dev, in this article we will dive into the Decimal datatype in SQL Server. We will explore its definition, its uses, and its limitations. By the end of this article, you will have a better understanding of the Decimal datatype and how it can improve the accuracy of your data.

Definition of Decimal Datatype

The Decimal datatype is a fixed-point datatype in SQL Server. It is used to store exact numeric values with a specified precision and scale. The precision is the total number of digits that can be stored in the decimal number, including both the whole numbers and the decimals. The scale is the number of digits that can be stored to the right of the decimal point.

For example, if the precision is set to 5 and the scale is set to 2, the Decimal datatype can store numbers from -999.99 to 999.99 with a maximum of two decimal places.

Precision and Scale

The precision and scale of the Decimal datatype can be specified when creating a column in a table or when casting values to the Decimal datatype. The maximum precision that can be specified is 38, and the maximum scale is equal to the precision.

The Decimal datatype is useful for financial and scientific applications that require high precision and accuracy in calculations. It is also useful for storing exact values such as measurements or counts, where rounding or approximation is not acceptable.

Decimal vs Float Datatypes

The Decimal datatype is often compared to the Float datatype in SQL Server. The Float datatype is a floating-point datatype that stores approximate numeric values. It is used to store scientific and engineering data that does not require exact precision.

While the Float datatype allows for a wider range of values than the Decimal datatype, it can lead to rounding errors and imprecision in calculations. The Decimal datatype, on the other hand, provides exact precision but may not be suitable for very large or very small numbers.

Uses of Decimal Datatype

The Decimal datatype is commonly used in financial applications, where accuracy and precision are crucial. It is also used in scientific and engineering applications that require exact measurements and calculations.

When designing a database schema, it is important to consider the precision and scale of the Decimal datatype for each column that will use it. Overly restrictive precision and scale can lead to unnecessary storage space and can limit the range of allowable values. On the other hand, inadequate precision and scale can result in rounding errors and loss of accuracy.

Example

Column Name	Data Type	Precision	Scale	Description
OrderTotal	Decimal	10	2	The total amount for an order.
ProductWeight	Decimal	5	1	The weight of a product in pounds.

Limitations of Decimal Datatype

The Decimal datatype is not without limitations. One limitation is its size – the Decimal datatype takes up more storage space than other numeric datatypes such as Int or Float. Another limitation is its range – the Decimal datatype can only store numbers within a certain range, and numbers outside that range must be stored using a different datatype.

Additionally, the Decimal datatype may not be suitable for very large or very small numbers. In these cases, a datatype such as Float or BigInt may be more appropriate.

Frequently Asked Questions

What is the difference between Decimal and Numeric datatypes in SQL Server?

There is no functional difference between the Decimal and Numeric datatypes in SQL Server. They are both fixed-point datatypes that store exact numeric values with a specified precision and scale. The only difference is in their name – Decimal is the name used in SQL Server, while Numeric is the name used in other database systems such as Oracle and MySQL.

How do I convert a Float value to a Decimal value in SQL Server?

You can convert a Float value to a Decimal value in SQL Server using the CAST or CONVERT function, specifying the Decimal datatype and the desired precision and scale. For example, to convert a Float value to a Decimal value with a precision of 10 and a scale of 2, you would use the following syntax:

SELECT CAST(FloatColumn AS Decimal(10,2)) FROM MyTable

What is the maximum precision and scale of the Decimal datatype in SQL Server?

The maximum precision that can be specified for the Decimal datatype in SQL Server is 38, and the maximum scale is equal to the precision. This means that a Decimal column can store up to 38 digits, including both the whole numbers and the decimals, and can have up to 38 digits to the right of the decimal point.

Can I use the Decimal datatype for dates and times in SQL Server?

No, the Decimal datatype is not suitable for storing dates and times in SQL Server. Dates and times should be stored using the DateTime or DateTimeOffset datatypes, which are specifically designed for this purpose.

Conclusion

The Decimal datatype is a useful datatype in SQL Server for storing exact numeric values with a specified precision and scale. It is commonly used in financial and scientific applications that require high precision and accuracy in calculations. When using the Decimal datatype, it is important to consider the precision and scale of each column to ensure that they are appropriate for the data being stored. While the Decimal datatype has some limitations, it can improve the accuracy and reliability of your data when used correctly.