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.
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...
so that both comparisons: x = NULL and x <> NULL evaluates to NULL(unknown). SQL implements three logical results, so SQL implementations must provide for a specialized three-valued logic (3VL).
NULL is not a value, and therefore cannot be compared to another value. where x is null checks whether x is a null value.
SQL supports NULL, a special value that is employed to represent the values of attributes that will be unknown or not apply to a tuple.
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
Команда IS NOT NULLпроверяет поле на не NULL.
Очень часто начинающие администраторы баз данных MySQL сталкиваються с проблемой обработки значения NULL из-за своего неправильного понимания этого значения. В этой статье попробуем разобрать что за зверь это значение NULL.
Оператор объединения с NULL ?? возвращает значение своего операнда слева, если его значение не равно 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.