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.
Then in the second table I have select ..., null as opt from... I know that I could have an empty string with '' as
The null character (also null terminator or null byte), abbreviated NUL or NULL, is a control character with the value zero.
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...
Number of null-s on change between passed and failed queries is the one attacker looks for.
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...
Note: A NULL value is different from a zero value or a field that contains spaces. A field with a NULL value is one that has been left
You can use the Oracle IS NOT NULL condition in either a SQL statement or in a block of PLSQL code.