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.
How can I run a MySQL query that selects everything that is not null? It would be something like … Do I just remove the all and go..?
The Background I was trying to solve the fourth realistic mission in hackthissite.org, and couldn't figure out exactly what SQL I should inject into the URL to retrieve the list of emails.
union all select null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null
Note: A NULL value is different from a zero value or a field that contains spaces.
Классический вариант внедрения SQL-кода, когда в уязвимый параметр передается выражение, начинающееся с «UNION ALL SELECT».
Даже выражение NULL != NULL не будет истинным, ведь нельзя однозначно сравнить одну неизвестность с другой. Кстати, ложным это выражение тоже не будет, потому что при вычислении условий Oracle не ограничивается состояниями ИСТИНА и ЛОЖЬ.
Use NULL in UNION injections for most data type instead of trying to guess string, date, integer etc. Be careful in Blind situtaions may you can understand error is coming from DB or
SELECT CONCAT(CAST(int_col AS CHAR), char_col); CONCAT() returns NULL if any argument is NULL. A NULL parameter hides all information contained in other parameters from the result. Sometimes this is not desirable; to avoid this, you can
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...