concatenate two database columns into one resultset column

Question

I use the following SQL to concatenate several database columns from one table into one column in the result set:

SELECT (field1 + \'\' + field2 + \'\' + field

Answer 1

Normal behaviour with NULL is that any operation including a NULL yields a NULL...

- 9 * NULL  = NULL  
- NULL + '' = NULL  
- etc  

To overcome this use ISNULL or COALESCE to replace any instances of NULL with something else..

SELECT (ISNULL(field1,'') + '' + ISNULL(field2,'') + '' + ISNULL(field3,'')) FROM table1