The DECIMAL data type is a commonly used data type in SQL that allows for the storage and manipulation of decimal numbers. It is often used when precision is required, such as in financial calculations or scientific measurements. In this article, we will explore how the DECIMAL data type works in SQL and how it can be used effectively.

## Defining a DECIMAL Column

To define a column with the DECIMAL data type in SQL, you specify the precision and scale. The precision determines the total number of digits that can be stored, while the scale determines the number of digits that can be stored after the decimal point. For example:

CREATE TABLE products ( price DECIMAL(10, 2) );

In this example, the price column has a precision of 10 and a scale of 2. This means that it can store up to 10 digits in total, with 2 digits after the decimal point.

## Inserting Values into a DECIMAL Column

When inserting values into a DECIMAL column, you need to ensure that the value being inserted does not exceed the specified precision and scale. For example:

INSERT INTO products (price) VALUES (19.99);

In this example, we are inserting a value of 19.99 into the price column. Since the column has a precision of 10 and a scale of 2, this value is within range and will be inserted successfully.

### Performing Arithmetic Operations

The DECIMAL data type allows for arithmetic operations such as addition, subtraction, multiplication, and division. When performing these operations on DECIMAL columns or values, it is important to consider precision and scale.

__Addition:__When adding two DECIMAL values, the resulting value will have the same precision and scale as the operand with the higher scale. For example:

SELECT price + 10.00 FROM products;

In this example, we are adding 10.00 to the price column. Since the price column has a scale of 2, the resulting value will also have a scale of 2.

__Subtraction:__Subtraction works in a similar way to addition. The resulting value will have the same precision and scale as the operand with the higher scale.__Multiplication:__When multiplying two DECIMAL values, the resulting value will have a precision equal to the sum of the precisions of both operands, and a scale equal to the sum of their scales.__Division:__Division works in a similar way to multiplication. The resulting value will have a precision equal to the sum of the precisions of both operands, and a scale equal to their difference.

## Conclusion

The DECIMAL data type in SQL is a powerful tool for working with decimal numbers that require precision. By understanding how to define columns with DECIMAL data type, insert values into them, and perform arithmetic operations on them, you can effectively work with decimal numbers in your SQL database.