LOG Function in SQL

The LOG function in SQL is used to return the logarithm of a number. The base of the logarithm can vary depending on how the function is used and the database system.

? Syntax

In MySQL:

LOG(number)             -- Natural log (base e)LOG(base, number)       -- Logarithm to the specified base

In SQL Server:

LOG(number)             -- Natural log (base e)LOG10(number)           -- Base-10 log

In Oracle:

LOG(number)             -- Natural log (base e)LOG(base, number)       -- Log to specific base (Oracle 12c+)

? Examples

1. Natural Log (base e):

SELECT LOG(10) AS natural_log;

Result:

2. Log with Custom Base:

SELECT LOG(10, 1000) AS log_result;

Result:

Because 10³ = 1000

?? Notes:

• The number must be greater than 0.

• Returns NULL or error if input is 0 or negative.

• LOG10() is specifically for base-10 in many databases (e.g., SQL Server, MySQL).

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