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...
1' UNION SELECT @--+ #The used SELECT statements have a different number of columns 1' UNION SELECT @,@--+ #The used
If a null pointer constant is converted to a pointer type, the resulting pointer, called a null pointer, is guaranteed to compare unequal to a pointer to any object or function.”
UNION ALL SELECT NULL, *, NULL, NULL FROM email. I understand what this does and why; the hacker needs to create a query that has the same number of columns as the query it's being merged with, and shifted around the * to make sure the emails are displayed. That's not my question.
CONCAT_NULL_YIELDS_NULL ON INSERT INTO Mytable(StringValue) SELECT COALESCE
null is nothing but internal Pointer with value zero.
11223344) UNION SELECT NULL,NULL,NULL,NULL WHERE 1=2 –- Если нет ошибки, значит синтаксис верный, т.е. используется MS SQL Server.
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".
NULL в языках программирования Си и C++ — макрос, объявленный в заголовочном файле stddef.h (и других заголовочных файлах). Значением этого макроса является зависящая от реализации константа нулевого указателя (англ. null pointer constant).
IS NULL вернёт истину, если операнд имеет значение NULL и ложь, если он им не является.