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...
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 blank during record creation!
Используйте NULL в UNION-инъекциях вместо попыток угадать строку, дату, число и прочее. Но будьте аккуратны при слепой инъекции, т.к. вы можете спутать ошибку БД и самого приложения. Некоторые языки, например ASP.NET, выдают ошибку при использовании значения NULL (т.к...
Select Group, Count(*) From [Data] Group by [Group]. The reason null shows 0 instead of 2 in this case is because each cell is counted as either 1 or null and null + null = null so the total of that group would also be null. However the column type is an integer so it shows up as 0.
IS NULL вернёт истину, если операнд имеет значение NULL и ложь, если он им не является.
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.
NULL в языках программирования Си и C++ — макрос, объявленный в заголовочном файле stddef.h (и других заголовочных файлах).
Значение Null не является ни пустой строкой (для символьного типа данных или типа данных datetime), ни нулевым значением (для
PostgreSQL does not allow null characters in char/text/varchar fields. e.g. when migrating the cischartingdb.institution table, the following error is...
Recently, some friends of mine said that NULL, '\0' and 0 are equal because they are all 0-value in ASCII.