select 1, 5+6, 1=6;


select null = 'Some string';

select '' = 'Some string';


select null || 'Some string';

select '' || 'Some string';


select *

from address

where address2 <> 'Moscow';


select *

from address a 

where address2 <> 'Moscow'

or address2  is null;

select *

from address a 

where address2 = null;


select '' = '';

select null = null;

select null = '';

select 1=1 and null = '';

select 1=1 or null = '';


select *

from address a 

where address2 in ('Moscow', '', null)


 

Последнее изменение: воскресенье, 20 июня 2021, 06:52