Decimal & Numeric Data Types in SQL Server: Everything You Need to Know

Decimal and numeric data types are commonly used in SQL Server for storing precise numerical data. These data types are ideal for storing monetary values, percentages, and other numeric data that requires a high degree of accuracy. In this article, we’ll explore the decimal and numeric data types in SQL Server, their key characteristics, and how to use them effectively in your database applications.

What are Decimal and Numeric Data Types?

Decimal and numeric data types are both used for storing precise numeric data. Both of these data types are exact when it comes to values, which is why they are often preferred over other data types like float and real.

The decimal data type is used for storing fixed-point values with a maximum total of 65 digits, with a maximum of 30 digits to the right of the decimal point. It is often used for storing monetary values because it allows for accurate calculations of decimal values. You can think of it as a scaled integer.

The numeric data type is similar to the decimal data type but allows for an even greater level of precision. It can store up to 38 digits, with the same maximum of 30 digits to the right of the decimal point.

Using Decimal and Numeric Data Types in SQL Server

When using decimal and numeric data types in SQL Server, it’s important to keep the following considerations in mind:

  • When defining a decimal or numeric column, you must specify both the precision and the scale. The precision is the total number of digits that can be stored, while the scale is the number of digits to the right of the decimal point.

  • Both the decimal and numeric data types support negative and positive values.

  • Decimal and numeric data types can be used in conjunction with other data types like int, float, and real for performing numeric calculations.

  • When performing calculations with decimal and numeric data types, take care to ensure that the scale is maintained.

Example

Let’s take a look at an example of using the decimal data type in SQL Server:

“`html
CREATE TABLE Sales (
SaleID INT,
SaleAmount DECIMAL(18,2)
);

INSERT INTO Sales VALUES (1, 10.55);
INSERT INTO Sales VALUES (2, 20.00);
INSERT INTO Sales VALUES (3, 30.25);

SELECT * FROM Sales;
“`

In this example, we’re creating a new table called “Sales” with two columns. The first column is an integer for the sale ID, while the second column is a decimal with a precision of 18 and a scale of 2 for storing the sale amount. We then insert three rows into the table with different sale amounts, and finally, we select all the data from the table.

FAQs

What is the difference between the decimal and numeric data types?

The decimal and numeric data types are very similar, with the main difference being that the numeric data type can store more digits than the decimal data type. Otherwise, the two data types behave exactly the same.

Why should I use decimal or numeric data types instead of float or real?

The decimal and numeric data types offer a high degree of precision that is not possible with float or real data types. Float and real data types are approximations and can lead to rounding errors when performing calculations.

What is the maximum precision and scale for decimal and numeric data types in SQL Server?

The maximum total digits that can be stored in a decimal or numeric data type in SQL Server is 65. The maximum number of digits to the right of the decimal point is 30.

Can decimal and numeric data types be used in conjunction with other data types?

Yes, decimal and numeric data types can be used in conjunction with other data types like int, float, and real for performing numeric calculations.

What should I be careful with when performing calculations with decimal and numeric data types?

When performing calculations with decimal and numeric data types, take care to ensure that the scale is maintained. If the scale is not maintained, the result of the calculation may be inaccurate.

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