In Oracle, the LOG() function returns the logarithm, base n2, of n1, where n2 is the first argument and n1 is the second.
Syntax
The syntax goes like this:
LOG(n2, n1)Where n2 can be any positive value other than 0 or 1, and n1 is any positive value.
Example
Here’s an example:
SELECT LOG(16, 73)
FROM DUAL;Result:
LOG(16,73) ___________________________________________ 1.54745613972000430746600429203996036707
Negative Values
Negative values result in an “out of range” error:
SELECT LOG(-16, 73)
FROM DUAL;Result:
Error starting at line : 1 in command - SELECT LOG(-16, 73) FROM DUAL Error report - ORA-01428: argument '-16' is out of range
Same for the second argument:
SELECT LOG(16, -73)
FROM DUAL;Result:
Error starting at line : 1 in command - SELECT LOG(16, -73) FROM DUAL Error report - ORA-01428: argument '-73' is out of range
Zero
Passing 0 also results in an “out of range” error:
SELECT LOG(0, 73)
FROM DUAL;Result:
Error starting at line : 1 in command - SELECT LOG(0, 73) FROM DUAL Error report - ORA-01428: argument '0' is out of range
And again, the same applies to the second argument:
SELECT LOG(16, 0)
FROM DUAL;Result:
Error starting at line : 1 in command - SELECT LOG(16, 0) FROM DUAL Error report - ORA-01428: argument '0' is out of range
Passing 1
Passing 1 for the second argument results in 0:
SELECT LOG(16, 1)
FROM DUAL;Result:
LOG(16,1)
____________
0
Passing 1 for the first argument results in an “out of range” error:
SELECT LOG(1, 2)
FROM DUAL;Result:
Error starting at line : 1 in command - SELECT LOG(1, 2) FROM DUAL Error report - ORA-01428: argument '1' is out of range
Expressions
The arguments can include expressions like this:
SELECT LOG(10 + 6, 12 * 30)
FROM DUAL;Result:
LOG(10+6,12*30) ___________________________________________ 2.12296327408241867769444932934625579835
Non-Numeric Arguments
The arguments can be any numeric data type or any nonnumeric data type that can be implicitly converted to a numeric data type.
Here’s an example of what happens when the arguments don’t satisfy that criteria:
SELECT LOG('Homer', 'Symptom')
FROM DUAL;Result:
Error starting at line : 1 in command -
SELECT LOG('Homer', 'Symptom')
FROM DUAL
Error report -
ORA-01722: invalid number
Null Arguments
LOG() returns null if any argument is null:
SET NULL 'null';
SELECT
LOG(null, 1024),
LOG(16, null),
LOG(null, null)
FROM DUAL;Result:
LOG(NULL,1024) LOG(16,NULL) LOG(NULL,NULL)
_________________ _______________ _________________
null null null
By default, SQLcl and SQL*Plus return a blank space whenever a null value occurs as a result of a SQL SELECT statement.
However, you can use SET NULL to specify a different string to be returned. Here I specified that the string null should be returned.
Missing Arguments
Calling LOG() with the wrong number of arguments, or without any arguments results in an error:
SELECT LOG()
FROM DUAL;Result:
Error starting at line : 1 in command - SELECT LOG() FROM DUAL Error at Command Line : 1 Column : 8 Error report - SQL Error: ORA-00909: invalid number of arguments 00909. 00000 - "invalid number of arguments" *Cause: *Action:
And:
SELECT LOG(10, 2, 3)
FROM DUAL;Result:
Error starting at line : 1 in command - SELECT LOG(10, 2, 3) FROM DUAL Error at Command Line : 1 Column : 8 Error report - SQL Error: ORA-00909: invalid number of arguments 00909. 00000 - "invalid number of arguments" *Cause: *Action: