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...
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
Now, if I do: SELECT CONCAT(FirstName, LastName, Email) as Vitals FROM MEMBERS.
Middlename is NULL and OP probably uses Oracle. Although Oracle treats zero-length character strings as nulls, concatenating a zero-length character string with another operand always results in the other operand, so null can result only from the concatenation of two null strings.
11223344) UNION SELECT NULL,NULL,NULL,NULL WHERE 1=2 –- Если нет ошибки, значит синтаксис верный, т.е. используется MS SQL Server.
Look at the following SELECT statement: SELECT ProductName, UnitPrice * (UnitsInStock + UnitsOnOrder) FROM Products
Существуют специальные операторы IS NULL и IS NOT NULL, которые позволяют производить сравнения с NULLами.
Команда IS NULL проверяет поле на NULL. Пример: SELECT * FROM workers WHERE salary IS NULL.
Как и в случае с обычными переменными, указатели не инициализируются при создании. Если значение не было присвоено, то указатель по умолчанию будет указывать на любой адрес, содержимым которого...
-1 UNION SELECT group_concat(username, 0x3a, password) FROM admin.