In Oracle, the ATAN() function returns the arctangent (inverse tangent) of its argument.

In other words, it returns the value whose tangent is the argument.

Syntax

The syntax goes like this:

ATAN(n)

Where n can be in an unbounded range.

Example

Here’s an example:

SELECT ATAN(0.7)
FROM DUAL;

Result:

                                   ATAN(0.7) 
____________________________________________ 
   0.610725964389208616543758876490236093837

Non-Numeric Argument

The argument can be any numeric data type or any nonnumeric data type that can be implicitly converted to a numeric data type.

Here’s what happens when we provide a non-numeric argument that can’t be converted to a numeric data type:

SELECT ATAN('One')
FROM DUAL;

Result:

Error starting at line : 1 in command -
SELECT ATAN('One')
FROM DUAL
Error report -
ORA-01722: invalid number

Null Values

Passing null to ATAN() returns null:

SET NULL 'null';

SELECT ATAN(null)
FROM DUAL;

Result:

   ATAN(NULL) 
_____________ 
         null

By default, SQLcl and SQL*Plus return a blank space whenever null 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.

Incorrect Argument Count

Calling ATAN() without passing any arguments returns an error:

SELECT ATAN()
FROM DUAL;

Result:

Error starting at line : 1 in command -
SELECT ATAN()
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 passing the wrong number of arguments results in an error:

SELECT ATAN(1, 2)
FROM DUAL;

Result:

Error starting at line : 1 in command -
SELECT ATAN(1, 2)
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: