sql injection "union select null" - CodeProject | To display as
Union select null, null, null, null, null, null, null from information_schema.tables. for a small database containing three tables. this instruction is used in sql injection I tried it and it worked but I didn't really know how it works can somebody help me...
Шпаргалка по SQL инъекциям | DefconRU
11223344) UNION SELECT NULL,NULL,NULL,NULL WHERE 1=2 –- Если нет ошибки, значит синтаксис верный, т.е. используется MS SQL Server.
c - Is (int *) 0 a null pointer? - Stack Overflow
If a null pointer constant is converted to a pointer type, the resulting pointer, called a null pointer, ... which covers (int *)0 as null pointer since cast is an
Do you use NULL or 0 (zero) for pointers in C++? - Stack Overflow
then using zero makes more sense (as in if you use NULL, you cannot logically use p && !q - you need to explicitly compare against NULL, unless you assume NULL is zero, in which case why use NULL). Is there any objective reason to prefer zero over NULL (or vice versa), or is all just personal preference?
NULL pointer in C - GeeksforGeeks
At the very high level, we can think of NULL as a null pointer which is used in C for various purposes.
c++ - Why is address zero used for the null pointer? - Stack Overflow
How can 0 be used for handling null pointers if that is the case? Why isn't a negative number null instead? Edit: A bunch of good answers.
Setting a char * to null | Forum
I think your nitpicking is incorrect: (char*)NULL is a null pointer, but "\0" is an empty string. "" is also an empty string, as is "\0abc".
SQL ISNULL(), NVL(), IFNULL() and COALESCE() Functions
Suppose that the "UnitsOnOrder" column is optional, and may contain NULL values. Look at the following SELECT statement: SELECT ProductName, UnitPrice * (UnitsInStock + UnitsOnOrder) FROM Products; In the example above, if any of the "UnitsOnOrder" values are NULL, the result will be NULL.
Что значит "NULL"? - C++ - Киберфорум
Подскажите, пожалуйста, что значит "NULL", и когда он применяется ? В примере ниже , насколько я понимаю, создаётся строка, и в этой строке нет элементов.
Заметка про NULL / Хабр | select col from ttt where col is not null
Существуют специальные операторы IS NULL и IS NOT NULL, которые позволяют производить сравнения с NULLами.