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Hello and welcome to this comprehensive guide on the Decimal Datatype in SQL Server. In this article, we will explore the significance of decimal datatype in SQL server, its implementation, and common queries related to it. As you read through this article, you will gain a better understanding of decimal datatype and learn how to use it to optimize your SQL Server database for better performance.

## What is a Decimal Datatype?

The decimal datatype is a precise numeric datatype in SQL Server that is used to store decimal numbers, which can be expressed with a fixed number of digits to the left and right of the decimal point. It is commonly used to store financial and monetary data, where precise calculations are essential. The decimal datatype in SQL Server is represented by the DECIMAL keyword and has a fixed precision and scale.

### Understanding Precision and Scale in Decimal Datatype

The precision and scale are two important attributes of the decimal datatype that determine the maximum number of digits that can be stored to the left and right of the decimal point. The precision represents the total number of digits that can be stored, while the scale represents the number of digits to the right of the decimal point. For example, if the decimal datatype has a precision of 10 and a scale of 2, it can store numbers with up to 10 digits, including 2 decimal places.

Precision | Scale | Maximum Storage Size | Range |
---|---|---|---|

1 – 9 | 0 – 9 | 5 bytes | -10^38 +1 to 10^38 -1 |

10 – 19 | 0 – 9 | 9 bytes | -10^38 +1 to 10^38 -1 |

20 – 28 | 0 – 9 | 13 bytes | -10^38 +1 to 10^38 -1 |

29 – 38 | 0 – 9 | 17 bytes | -10^38 +1 to 10^38 -1 |

### How to Create a Decimal Datatype in SQL Server

The following syntax is used to create a decimal datatype in SQL Server:

`DECIMAL(Precision, Scale)`

For example, the following code creates a decimal datatype with a precision of 10 and a scale of 2:

`CREATE TABLE MyTable (MyColumn DECIMAL(10,2));`

## Implementing Decimal Datatype in SQL Server

Now that we understand the basics of decimal datatype in SQL Server, let’s explore how it can be implemented in database design and querying.

### Using Decimal Datatype in Database Design

The decimal datatype is commonly used in database design for storing financial and monetary data that requires precise calculations. For example, a table that stores customer orders may have columns such as order total, tax amount, and shipping costs, which can be stored using decimal datatype for accurate calculations.

### Queries Involving Decimal Datatype

Queries involving decimal datatype can be tricky if the precision and scale are not correctly set. Here are some common queries involving decimal datatype and their solutions:

### Query 1: How to Insert Decimal Values into a Table?

The following code demonstrates how to insert decimal values into a table:

`INSERT INTO MyTable (MyColumn) VALUES (1234.56);`

### Query 2: How to Round a Decimal Value?

The following code demonstrates how to round a decimal value:

`SELECT ROUND(MyColumn, 2) FROM MyTable;`

### Query 3: How to Calculate Sum of Decimal Values?

The following code demonstrates how to calculate the sum of decimal values:

`SELECT SUM(MyColumn) FROM MyTable;`

### Query 4: How to Calculate Average of Decimal Values?

The following code demonstrates how to calculate the average of decimal values:

`SELECT AVG(MyColumn) FROM MyTable;`

## FAQs About Decimal Datatype in SQL Server

### Q1: What is the difference between Decimal and Numeric Datatype?

A: The Decimal and Numeric datatypes are functionally equivalent in SQL Server. They both store fixed precision and scale decimal numbers. The only difference between them is their names.

### Q2: What happens if precision and scale of Decimal Datatype are not correctly set?

A: If the precision and scale of decimal datatype are not correctly set, it can result in rounding errors and inaccurate calculations. It is essential to correctly set the precision and scale according to the values being stored.

### Q3: What is the maximum precision and scale of Decimal Datatype?

A: The maximum precision of decimal datatype in SQL Server is 38, while the maximum scale is 38.

### Q4: Can Decimal Datatype store negative numbers?

A: Decimal datatype can store both positive and negative numbers.

### Q5: Can Decimal Datatype be used as a primary key?

A: Yes, decimal datatype can be used as a primary key.

## Conclusion

In conclusion, the decimal datatype is a precise numeric datatype in SQL Server that is commonly used to store financial and monetary data for accurate calculations. It has a fixed precision and scale, which must be correctly set to ensure accurate calculations. This article covered the implementation and usage of decimal datatype in SQL Server, including common queries involving decimal datatype and FAQS. We hope this article has been informative and helpful to you in using decimal datatype in your SQL Server database.