Oracle/PLSQL: NVL Function
In Oracle/PLSQL, the NVL function lets you substitute a value when a null value is encountered.
The syntax for the NVL function is:
NVL( string1, replace_with )
string1 is the string to test for a null value.
replace_with is the value returned if string1 is null.
- Oracle 11g, Oracle 10g, Oracle 9i, Oracle 8i
select NVL(supplier_city, 'n/a') from suppliers;
The SQL statement above would return 'n/a' if the supplier_city field contained a null value. Otherwise, it would return the supplier_city value.
select supplier_id, NVL(supplier_desc, supplier_name) from suppliers;
This SQL statement would return the supplier_name field if the supplier_desc contained a null value. Otherwise, it would return the supplier_desc.
select NVL(commission, 0) from sales;
This SQL statement would return 0 if the commission field contained a null value. Otherwise, it would return the commission field.
Frequently Asked Questions
Question: I tried to use the NVL function through VB to access Oracle DB.
To be precise,
select NVL(Distinct (emp_name),'AAA'),................ from.................
I got an oracle error when I use distinct clause with NVL, but when I remove distinct it works fine.
Answer: It is possible to the use the DISTINCT clause with the NVL function. However, the DISTINCT must come before the use of the NVL function. For example:
select distinct NVL(emp_name, 'AAA') from employees;
Hope this helps!
Question: Is it possible to use the NVL function with more than one column with the same function call? To be clear, if i need to apply this NVL function to more than one column like this:
NVL(column1;column2 ...... , here is the default value for all )
Answer: You will need to make separate NVL function calls for each column. For example:
select NVL(table_name, 'not found'), NVL(owner, 'not found') from all_tables;