how to use to_number function in oracle database query

The TO_NUMBER function in Oracle SQL / PLSQL is used to convert a string to a number data type

The Syntax for the TO_NUMBER function in Oracle SQL / PLSQL is:

SELECT TO_NUMBER(string1, [FORMAT_MASK], [NLS_LANGUAGE])
FROM table_name;

• string1 is the string that has to be converted to number
• FORMAT_MASK is optional; it is used to convert the string1 to number.
• NLS_LANGUAGE is also optional and is used to convert the string1 to number.

Example 1:

SELECT TO_NUMBER('123.456',999.999)
FROM DUAL; 

Will return “123.456”

Example 2:

SELECT TO_NUMBER('123.4',999.9)
FROM DUAL;

Will return “123.4”

Example 3:

SELECT TO_NUMBER('123',999.9)
FROM DUAL;

Will return “123”