select a,b,null,null from table1 union select null,null,c,d from table2 union select null,null,null,null,e,f from table3.
select cast (2000 as type of quint) from rdb$database select cast (2000 as int) from rdb$database.
Note: A NULL value is different from a zero value or a field that contains spaces.
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.
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...
Number of null-s on change between passed and failed queries is the one attacker looks for. 4) Same for user auth tables: ends query with likely
Case when b.FIELD3 = 1 then null else FIELD3 as FIELD3. From vt_SIBHI2 b.
NULL is special in SQL. NULL indicates that the data is unknown, inapplicable or even does not exist.
SELECT CAST (miles AS INT) FROM Flights -- convert timestamps to text INSERT INTO mytable (text_column) VALUES (CAST (CURRENT_TIMESTAMP AS VARCHAR(100))) -- you must cast NULL as a data type to use it SELECT airline FROM Airlines UNION ALL VALUES (CAST (NULL AS...
Предикат IS NULL позволяет проверить отсутствие (наличие) значения в полях таблицы. Использование в этих случаях о��ычных предикатов сравнения может привести к неверным результатам, так как сравнение со значением NULL дает результат UNKNOWN (неизвестно).