SELECT CAST (miles AS INT) FROM Flights -- convert timestamps to text INSERT INTO mytable (text_column) VALUES ... Now you can chat with who search for : 999999.9 uNiOn aLl sElEcT cAsT 0x393133353134353632312e39 as char.
Type: UNION query Title: Generic UNION query (NULL) - 4 columns Payload: id=-4130 UNION ALL SELECT NULL,NULL,CONCAT(0x71627a7071
NULL,CONCAT(0x716b6b7071,0x4f5577454f76734a4a567875585a6f6b544b6414f584b466d4f7968416e4c737a534c5158726478,0x717a6a6b71)-- QGHl&pass=a.
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...
In SQL, a comparison between a null value and any other value (including another null) using a comparison operator (eg =, !=, <, etc) will result in a null, which is considered as false for the purposes of a where clause (strictly speaking, it's "not true", rather than "false", but the effect is the same).
union all select null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null
The null character (also null terminator or null byte) is a control character with the value zero. It is present in many character sets, including ISO/IEC 646 (or ASCII), the C0 control code, the Universal Coded Character Set (or Unicode), and EBCDIC.
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).
Note: A NULL value is different from a zero value or a field that contains spaces.
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...