sql - Union to handle NULL values - Stack Overflow
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.
SQL-Injection-Payloads/sqli-misc.txt at master...
999999.9+union+all+select+%27R3DM0V3_hvj_injection',null
mysql - Site has been hacked via SQL Injection - Stack Overflow
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 columns. As a result, they just used `NULL values to populate those columns.
SQL NULL Values - IS NULL and IS NOT NULL
Note: A NULL value is different from a zero value or a field that contains spaces.
SQL is null and = null - Stack Overflow
What is the difference between … and … and why does the latter not work?
php - A customers site had a big mysql injection attack on it, just want...
union all select null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null
Modern SQL: NULL — purpose, comparisons, NULL in expressions...
SQL’s NULL indicates absent data. NULL propagates through expressions and needs distinct comparison operators.
Заметка про NULL / Хабр
Даже выражение NULL != NULL не будет истинным, ведь нельзя однозначно сравнить одну неизвестность с другой. Кстати, ложным это выражение тоже не будет, потому что при вычислении условий Oracle не ограничивается состояниями ИСТИНА и ЛОЖЬ.
Null (SQL) - Wikipedia
Null (or NULL) is a special marker used in Structured Query Language to indicate that a data value does not exist in the database. Introduced by the creator of the relational database model, E. F. Codd...
R null values: NULL, NA, NaN, Inf | R-bloggers
R language supports several null-able values and it is relatively important to understand how these