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.
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.
I have a table with three fields, FirstName, LastName and Email. Here's some dummy data: … Now, if I do: … Vitals for Joe is null, as there is a single null field. How do you overcome this behaviour?
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..?
If I have the table … This will display Firstname-Middlename-Surname e.g. … The second one (Jane’s) displays correct, however since John doesn’t have a middlename, I want it to ignore the second dash.
union all select null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null
What is the difference between … and … and why does the latter not work?
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
Note: A NULL value is different from a zero value or a field that contains spaces.