The SQL DECIMAL data type is used to represent fixed-point numeric values with exact precision. It is commonly used in financial and accounting applications where precision and accuracy are of utmost importance.
The DECIMAL data type is also known as NUMERIC, and it is specified using the syntax DECIMAL(P,S), where P represents the total number of digits that can be stored (precision), and S represents the number of digits that can be stored after the decimal point (scale). For example, DECIMAL(10,2) can store up to 10 digits, with 2 digits after the decimal point, providing a range of -9999999.99 to 9999999.99.
One important aspect of the DECIMAL data type is that it has fixed precision, which means that it always stores the exact number of digits specified by the precision, even if some of the digits are zeros. This feature makes the DECIMAL data type ideal for calculations that require exact precision, such as financial transactions.
In SQL, arithmetic operations involving DECIMAL values result in a DECIMAL value with the same precision and scale as the operands. For example, if you add two DECIMAL(10,2) values, the result will also be a DECIMAL(10,2) value.
When creating tables with DECIMAL columns, it is important to choose the appropriate precision and scale based on the specific requirements of the application. If the precision and scale are too high, it can lead to inefficient use of storage space and slow performance, while if they are too low, it can lead to rounding errors and loss of precision.
In summary, the SQL DECIMAL data type is a valuable tool for storing and manipulating fixed-point numeric values with exact precision. Its fixed precision and range make it a preferred choice for financial and accounting applications, where precision and accuracy are critical.