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...
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 journey.id, null AS departure, TIME_FORMAT(ADDTIME(journey.departure, SEC_TO_TIME(SUM(l1.elapsed))), '%H:%i') AS arrival FROM
Yes, by using COALESCE. SELECT COALESCE(null_column, 0) AS null_column FROM whatever; COALESCE goes through the list of values you give it, and returns the first non-null value.
In general, every NULL value is taken into account to vary from each alternative NULL in the database.
i am trying to do union i get data with null values and i want do not want it to show in result. such as: column1 col2 col3 col4 col5 col6 test1 1 2 3 null 6 test2 2
union all select null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null
Тем не менее, NULL, как NULL-значение, часто используется в SQL. Предположим, появился покупатель, которому еще не назначен продавец. Чтобы констатировать этот факт, нужно ввести значение NULL в поле snum, а реальное значение включить туда позже...
Note: A NULL value is different from a zero value or a field that contains spaces.
Оператор объединения с NULL ?? возвращает значение своего операнда слева, если его значение не равно null.