In MySQL, the DOUBLE data type is used to store double-precision floating-point numbers. It is a numeric data type that can represent a wide range of values with a high degree of precision. Double-precision means that these numbers are stored with twice the precision of the FLOAT data type.

DOUBLE key points

Here are some key points of the DOUBLE data type in MySQL:

Precision and Range

The DOUBLE data type is a 64-bit approximate numeric data type.
It can store numbers with a precision of approximately 15 decimal places.
The range of values that can be stored in a DOUBLE column is from -1.7976931348623157 x 10^308 to -2.2250738585072014 x 10^-308 for negative values, and from 2.2250738585072014 x 10^-308 to 1.7976931348623157 x 10^308 for positive values.

Storage Size

The DOUBLE data type requires 8 bytes of storage.
This is in contrast to the FLOAT data type, which requires 4 bytes of storage and has a lower precision.

Usage

DOUBLE is commonly used when a higher degree of precision is required compared to the FLOAT data type.
It is suitable for situations where accurate representation of decimal numbers is crucial, such as in financial applications or scientific calculations.

Syntax

CREATE TABLE example_table (
    column1 DOUBLE,
    column2 DOUBLE(10,2)  -- The optional (M, D) specifier can be used to specify the display width and number of decimal places.
);

Example

CREATE TABLE product_prices (
    product_id INT,
    price DOUBLE(8,2)
);

INSERT INTO product_prices (product_id, price) 
VALUES
    (1, 19.99),
    (2, 15.50),
    (3, 49.75);

In this example, the price column is defined as DOUBLE(8,2), meaning it can store up to 8 digits in total with 2 digits after the decimal point.

It’s important to note that while the DOUBLE data type provides high precision, it is not suitable for all scenarios. For exact numeric calculations where precision is critical, the DECIMAL data type might be more appropriate, as it avoids the rounding errors associated with floating-point representations.