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...
...NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULl, NULL-- Можно использовать CAST
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
...null, null, null, null from information_schema.tables. for a small database containing three tables. this
IS NULL вернёт истину, если операнд имеет значение NULL и ложь, если он им не является.
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.”
Использование UNION[править | править код]. Язык SQL позволяет объединять результаты нескольких запросов при помощи оператора UNION.
The IS NULL operator is used to test for empty values (NULL values). The following SQL lists all customers with a NULL value in the "Address" field: Example. SELECT CustomerName, ContactName, Address FROM Customers WHERE Address IS NULL
However, it was unknown outside the Soviet Union and usually Harold Lawson is credited with the
NULL не является ни пустой строкой (для типов данных character или datetime), ни