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 1 from(select count(*), concat(( select( select unhex(hex
99 or 1=1 union select null, concat(table_name,0x0a,column_name) from information_ schema.columns - since where clause cannot be used
UNION ALL SELECT NULL, *, NULL, NULL FROM email. I understand what this does and why; the hacker needs to create a query that has the same number
Select column_name, count(column_name) as count_not_null from mydb.information_schema.columns where
null, is just a place holder that is used because a union statement requires that the number of fields match the 1st query that it’s appending to.
Пример: SELECT header, txt FROM news UNION ALL SELECT name, pass FROM members Это позволит объединить результаты из таблиц news
SELECT column_names FROM table_name WHERE column_name IS NOT NULL
Returns NULL if either argument is NULL. This function does not work properly if the first argument
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...