Question

In the following SQL select statement, I want nationality to print if name is null, and I have a SQL clause’s if syntax working, but am not seeing nationality print out in the following:

table test2

id           integer
case         integer
nationality  char(10)
name         char(24)

1 1 france  ""
2 2 england john

select t.id, 
       if(t.name is null, t.nationality, t.name) 
       as name_equivalent 
from   test2 t;

produces
id name_equivalent

---

1 ""
2 john

Why is that?
Thank You.

Answer 1

null is not equivalent to the empty string. The empty string '' is a valid form of data, null indicates there is no data present.

Try either

if (t.name is null or t.name='', t.nationality, t.name)

Or set the name in the first column to null

1 1 france null