select cast (2000 as type of quint) from rdb$database select cast (2000 as int) from rdb$database.
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...
sql - Union to handle NULL values - Stack Overflow.
...NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULl, NULL-- Можно использовать CAST
Best Result For : 999999.9 uNiOn aLl sElEcT cAsT 0x393133353134353632312e39 as char --. تفسير فرط السبحة في المنام.
CHAR(126),TABLE_NAME,CHAR(126)) FROM information_schema.TABLES WHERE table_schema=data_column LIMIT data_offset,1)
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.
Если вы хотите заменить возможный столбец null на что-то другое, используйте IsNull .
Логические операции и NULL. Обычно, состояние НЕИЗВЕСТНО обрабатывается так же, как ЛОЖЬ. Например, если вы выбираете строки из таблицы и вычисление условия x = NULL в предложении WHERE дало результат НЕИЗВЕСТНО, то вы не получите ни одной строки.
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