Learn how to use the Oracle/PLSQL NVL function with syntax and examples.
The Oracle/PLSQL NVL function lets you substitute a value when a null value is encountered.
The syntax for the Oracle/PLSQL 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.
The NVL function can be used in the following versions of Oracle/PLSQL:
Let's look at some Oracle NVL function examples and explore how to use the NVL function in Oracle/PLSQL.
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.
Another example using the NVL function in Oracle/PLSQL is:
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.
A final example using the NVL function in Oracle/PLSQL is:
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.
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;