sql - Union to handle NULL values - Stack Overflow
select a,b,null,null from table1 union select null,null,c,d from table2 union select null,null,null,null,e,f from table3.
sql - WHERE all IS NOT NULL - Stack Overflow | Post as a guest
How can I run a MySQL query that selects everything that is not null? It would be something like … Do I just remove the all and go..?
coding style - SQL - Select null as FIELDNAME? - Stack Overflow
I have come across some code that says … What exactly is this doing? Is it getting the field names unitcost and markup? Why would you use "select null as..."? New to this sorry. Thanks.
sql union all data type error with nulls - Stack Overflow
Then in the second table I have select ..., null as opt from... I know that I could have an empty string with '' as
sql - CONCAT'ing NULL fields - Stack Overflow | Post as a guest
I have a table with three fields, FirstName, LastName and Email. Here's some dummy data: … Now, if I do: … Vitals for Joe is null, as there is a single null field. How do you overcome this behaviour?
SQL is null and = null - Stack Overflow
What is the difference between … and … and why does the latter not work?
SQL NULL Values - IS NULL and IS NOT NULL
Note: A NULL value is different from a zero value or a field that contains spaces.
Заметка про NULL / Хабр
Специальное значение NULL означает отсутствие данных, констатацию того факта, что значение неизвестно. По умолчанию это значение могут принимать столбцы и переменные любых типов, если только на них не наложено ограничение NOT NULL.
Использование значения NULL в условиях поиска | Интерактивный...
Предикат IS NULL позволяет проверить отсутствие (наличие) значения в полях таблицы. Использование в этих случаях обычных предикатов сравнения может привести к неверным результатам, так как сравнение со значением NULL дает результат UNKNOWN (неизвестно).
SET CONCAT_NULL_YIELDS_NULL (Transact-SQL)... | Microsoft Docs
In a future version of SQL Server CONCAT_NULL_YIELDS_NULL will always be ON and any applications that explicitly set the option to OFF will generate an error.