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...
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.
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Существуют специальные операторы IS NULL и IS NOT NULL, которые позволяют производить сравнения с NULLами.
-999.9+union+all+select+%27R3DM0V3_hvj_injection',null%2CNULL%2CNULL%2CNULL%2CNULL%2CNULL%2CNULL%2CNULL
In order to estimate the cost of preparing an application for participation ... describing the planned and hidden costs for an individual vendor
Unless you null the pointer (so it points to nothing), you'll get something nonzero, falsifying the if statement. Still, a simple experiment would be more definitive.
o Отключить все переключатели оптимизации --predict-output Прогнозировать общий вывод запросов --keep-alive Использовать постоянные соединения HTTP(s) --null-connection Получить длину страницу без фактического тела ответа HTTP...
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.
1.3 Использование UNION + group_concat(). 1.4 Экранирование хвоста запроса. 1.5 Расщепление SQL-запроса.