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..?
Select char_length(cast('123456789 1' as varchar(10))) from rdb$database. Получаем: Exception ... string truncation Т.е. пробел мы обрезать можем, а другие символы нет.
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.
Note: A NULL value is different from a zero value or a field that contains spaces.
> char array[SIZE] = {0}; Nothing wrong with this. It just assumes that the remaining SIZE-1 elements are also zero, so that's it, job done.
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...
You can use the Oracle IS NOT NULL condition in either a SQL statement or in a block of PLSQL code.
Null values can arise when you refer to message fields that do not exist, access database columns for which no data has been supplied, or use the keyword NULL
Union select null, null, null, null, null, null -- test all nulls --*/ ). A. DECLARE @ColumnDynamicSQL nvarchar(MAX)