In SQL, the data type used to represent currency values is **DECIMAL**. The DECIMAL data type is commonly used for storing monetary values, as it allows for precise calculations and avoids rounding errors that can occur with other data types like __FLOAT__ or __DOUBLE__.

## DECIMAL Data Type

The DECIMAL data type is a fixed-point numeric data type, which means that it represents numbers with a fixed number of digits before and after the decimal point. When defining a DECIMAL column in a SQL table, you need to specify two parameters: the total number of digits and the number of digits after the decimal point. For example, DECIMAL(10, 2) represents a number with a total of 10 digits, out of which 2 are after the decimal point.

### Example:

CREATE TABLE Products ( ProductID INT, Price DECIMAL(10, 2) );

In the above example, we have created a table called **Products** with two columns: **ProductID** and **Price**. The **Price** column is defined as DECIMAL(10, 2), indicating that it can store a currency value with up to 10 total digits and 2 digits after the decimal point.

## Working with Currency Values in SQL

To insert currency values into a DECIMAL column in SQL, you need to specify the value using the appropriate format. In most cases, currency values are represented using the standard decimal notation.

### Example:

INSERT INTO Products (ProductID, Price) VALUES (1, 99.99); INSERT INTO Products (ProductID, Price) VALUES (2, 49.95);

In the above example, we are inserting two rows into the **Products** table. The **Price** column is assigned currency values using the decimal notation.

When performing calculations or comparisons involving currency values, it is important to remember that SQL treats DECIMAL values as numeric types. This means that you can use arithmetic operators like +, -, *, / to perform calculations on currency values.

### Example:

SELECT Price * 0.1 AS TaxAmount FROM Products;

The above query calculates and returns the tax amount (10% of the price) for each product in the **Products** table.

## Rounding and Precision

One advantage of using the DECIMAL data type for representing currency values is that it allows you to control rounding and precision. By specifying the appropriate number of digits after the decimal point, you can ensure that calculations involving currency values are accurate.

However, it is important to note that DECIMAL columns have a maximum precision and scale. The precision represents the total number of digits (both before and after the decimal point), and the scale represents the number of digits after the decimal point. If a value exceeds the specified precision or scale, it may be rounded or truncated to fit within the column’s constraints.

## In Summary

The DECIMAL data type in SQL is commonly used for representing currency values. It offers precise calculations and avoids rounding errors that can occur with other data types. When working with currency values in SQL:

- Use DECIMAL data type with appropriate precision and scale.
- Insert currency values using decimal notation.
- Perform calculations using arithmetic operators.
- Be aware of rounding and precision limitations.

By utilizing the DECIMAL data type effectively, you can ensure accurate representation and manipulation of currency values in your SQL database.