...NULL,NULL,NULL,NULL,NULL,NULL,NULL,CONCAT(0x717a6a7171
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...
id=1 LIMIT 1,1 UNION ALL SELECT NULL, NULL, CONCAT(0x3a717a753a,0x58797556477664726652
NULL is not a value, and therefore cannot be compared to another value. where x is null checks whether x is a null value.
Update mytable set mycolumn = null where mycolumn = 0. But do you mean in all columns? That will be more work and best you just create separate statements for
Тем не менее, NULL, как NULL-значение, часто используется в SQL. Предположим, появился покупатель, которому еще не назначен продавец.
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.
Команда IS NULL проверяет поле на не NULL.
Не используйте для поиска значени�� NULL выражение ISNULL,Do not use ISNULL to find NULL values. вместо него следует использовать
Note: A NULL value is different from a zero value or a field that contains spaces.