How to Efficiently Generate Random Values Within a Range in MySQL?

Generating Random Values Between Two Values in MySQL

Seeking a SQL query that can return a random value within a specified range,

SELECT RAND(min_v, max_v) foo [..]

is not a valid approach as RAND serves a different purpose. While the formula (RAND() * (max-min)) min seems promising, it produces float values that require rounding, complicating the process.

MySQL's Rounding Method: The Optimal Solution

Using ROUND((RAND() * (max-min)) min) is the preferred method in MySQL, ActionScript, JavaScript, and Python for generating random values within a range. This approach is highly efficient and convenient, simplifying the task compared to PHP alternatives.

PHP Versus MySQL Performance

To determine whether PHP or MySQL is more suitable for generating a large number of random values, a benchmark test was conducted.

For 100,000 iterations:

• MySQL Select took approximately 0.019 seconds.
• PHP Select took approximately 0.02 seconds.

Therefore, MySQL outperforms PHP slightly (by about 2-3%) when only the random value is needed. However, if additional columns are returned, MySQL falls behind PHP by 3-4%.

Optimization Guidance

For optimal performance, use MySQL to generate random values if only the random value is required. If additional columns are needed, consider using PHP for better efficiency.

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