select cast (2000 as type of quint) from rdb$database select cast (2000 as int) from rdb$database. If TYPE OF is used with a (VAR)CHAR type, its character.
select cast (2000 as type of quint) from rdb$database select cast (2000 as int) from rdb$database. If TYPE OF is used with a (VAR)CHAR type, its character.
0x31303235343830303536 is NULL - they are just matching the number of columns in your existing query. If you had SELECT * FROM users and users had 4 columns, the UNION must also have 4
Классический вариант внедрения SQL-кода, когда в уязвимый параметр передается выражение, начинающееся с «UNION ALL SELECT».
Note: A NULL value is different from a zero value or a field that contains spaces.
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), abbreviated NUL or NULL, is a control character with the value zero. It is present in many character sets, including ISO/IEC 646 (or ASCII)...
R language supports several null-able values and it is relatively important to understand how these values behave, when making data pre-processing and data munging.
In MySQL, 0 or NULL means false and anything else means true. The default truth value from a boolean operation is 1. This special treatment of NULL is why, in the previous section, it was necessary to determine which animals are no longer alive using death IS NOT NULL instead of death <> NULL.
Связано ли это с типом null и с тем, как он обрабатывается, или с тем, как выполняются операции сравнения значений? В итоге я решил докопаться до сути происходящего и начал рыться в единственном источнике истины для JavaScript — в спецификации ECMA.