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...
999999.9" //union//**/union/**/all/**/select/**/null, null, null, null, null..."
...null, null, null, null from information_schema.tables. for a small database containing three tables. this
Confusing SQL error in SELECT NULL, *, NULL, NULL - Stack Overflow
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.
Setting a char * to null | Forum
that's wrong though. (char*)NULL isn't a string at all, it's a null pointer. this isn't a string either even though it's an array of char.
NULL pointer in C - GeeksforGeeks
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.”
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.
The SQL Injection Knowledge Base | Tables and Columns
SELECT username FROM Users WHERE id = '-1' UNION SELECT MID(GROUP_CONCAT(0x3c62723e
LEFT JOIN / IS NULL vs. NOT IN vs. NOT EXISTS: nullable columns
When inner.value is marked as NOT NULL, all these queries are semantically equivalent and with proper indexing have similarly optimized execution plans in MySQL. Now, what if inner.value is not nullable and does contain some NULL values? Let's create some sample tables: Table creation details.
SQL ISNULL(), NVL(), IFNULL() and COALESCE() Functions
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Обработка значений NULL - ADO.NET | Microsoft Docs
Если строго типизированное значение NULL может быть преобразовано в тип данных столбца с помощью операторов неявного приведения, то назначение должно