如何為特定範圍定義 MySQL DECIMAL 欄位？

Understanding and Using MySQL DECIMAL

Precise numerical data storage is essential in financial and scientific applications. MySQL's DECIMAL data type provides an accurate representation of real numbers and avoids the pitfalls associated with DOUBLE columns.

Defining a DECIMAL Column for a Specific Range

To define a DECIMAL column capable of representing values from 00.0001 to 99.9999, use the following syntax:

CREATE TABLE your_table (
    your_column DECIMAL(6,4) NOT NULL
);

DECIMAL Syntax and Usage

DECIMAL columns are defined using the DECIMAL(M, D) format, where:

• M (precision) represents the maximum number of digits in the column.
• D (scale) indicates the number of digits to the right of the decimal point.

Advantages of DECIMAL over DOUBLE

Unlike DOUBLE, which approximates real numbers using a floating-point representation, DECIMAL columns store exact values. This ensures precision and avoids potential inaccuracies in financial and numeric calculations.

Additional Notes

• Unsigned is deprecated for DECIMAL columns in MySQL 8.0.17+.
• For more comprehensive information, refer to the official MySQL documentation on DECIMAL.

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