MySQL LOG() Function

The LOG() function in MySQL is used to return the logarithm of a specified number, either with the natural logarithm (base e) or with a specified base.

Syntax

LOG(number)

or

LOG(base, number)

Definition and Usage

• The LOG() function computes the natural logarithm (logarithm to the base e) if only one argument is provided.
• If two arguments are provided, the LOG() function computes the logarithm of the number to the specified base.
• The first argument (number) must be greater than 0, and the second argument (base) must be greater than 1 for valid results.

Parameter Values

Technical Details

• Works in: From MySQL 4.0
• Return Value: A floating-point value representing the logarithm of the number (based on the specified base).

Examples

Example 1: Return the natural logarithm of 2

SELECT LOG(2);

Result:

LOG(2): 0.693147

Explanation: The natural logarithm of 2 is approximately 0.693147.

Example 2: Return the logarithm of 4 with base 2

SELECT LOG(2, 4);

Result:

LOG(2, 4): 2

Explanation: The logarithm of 4 to the base 2 is 2, as 2^2 = 4.

Example 3: Return the natural logarithm of 10

SELECT LOG(10);

Result:

LOG(10): 2.302585

Explanation: The natural logarithm of 10 is approximately 2.302585.

Example 4: Return the logarithm of 1000 to base 10

SELECT LOG(10, 1000);

Result:

LOG(10, 1000): 3

Explanation: The logarithm of 1000 to the base 10 is 3, as 10^3 = 1000.

Related Functions

• LN(): Returns the natural logarithm of a number (same as LOG() with base e).
• EXP(): Returns e raised to the power of the specified number.

Usage Notes

• The LOG() function is widely used in scientific, financial, and statistical calculations that involve logarithmic growth, compounding, and other processes.
• The second argument (base) allows you to calculate logarithms to any base (e.g., base 10 for common logarithms). If omitted, the function defaults to the natural logarithm.