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.
A field with a NULL value is a field with no value. If a field in a table is optional, it is possible to insert a new record or update a record without adding a value to this
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...
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...
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 результат UNKNOWN (неизвестно).
The Oracle IS NOT NULL condition is used to test for a NOT NULL value. You can use the Oracle IS NOT NULL
Now this column contains alphanumeric values as well as some nulls. In my application we consider NULL is equal to NULL. A user gives an input and then i have to
R language supports several null-able values and it is relatively important to understand how these