select a,b,null,null from table1 union select null,null,c,d from table2 union select null,null,null,null,e,f from table3.
select cast (2000 as type of quint) from rdb$database select cast (2000 as int) from rdb$database.
999999.9' union all select 999,2 and '0'='0 где купить в аптеках, Поиск и заказ лекарств в аптеках Санкт-Петербурга и Ленинградской области онлайн, бронирование и доставка лекарств.
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...
Предикат IS NULL позволяет проверить отсутствие (наличие) значения в полях таблицы. Использование в этих случаях обычных предикатов сравнения может привести к неверным результатам, так как сравнение со значением NULL дает результат UNKNOWN (неизвестно).
Number of null-s on change between passed and failed queries is the one attacker looks for. 4) Same for user auth tables: ends query with likely non-existent
A field with a NULL value is a field with no value. If a field in a table is optional, it is possible to insert a new record or update a record without adding a value to this
Оператор объединения с NULL ?? возвращает значение своего операнда слева, если его значение не равно null.
Null values can be used as a condition in the WHERE and HAVING clauses. For example, a WHERE clause can specify a column that, for some rows, contains a null value. A basic comparison predicate using a column that contains null values does not select a row that has a null value for the column.
The null character (also null terminator or null byte) is a control character with the value zero. It is present in many character sets, including ISO/IEC 646 (or ASCII), the C0 control code, the Universal Coded Character Set (or Unicode), and EBCDIC.