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.
In postgres, I'm getting an error when I try to union two tables where one table has a column (Amount) containing double precision data type...
union all select null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null
The Background I was trying to solve the fourth realistic mission in hackthissite.org, and couldn't figure out exactly what SQL I should inject into the URL to retrieve the list of emails.
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
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...
Note: A NULL value is different from a zero value or a field that contains spaces.
11223344) UNION SELECT NULL,NULL,NULL,NULL WHERE 1=2 –- No Error - Syntax is right. MS SQL Server Used.
SQL’s NULL indicates absent data. NULL propagates through expressions and needs distinct comparison operators.
Предикат IS NULL позволяет проверить отсутствие (наличие) значения в полях таблицы. Использование в этих случаях обычных предикатов сравнения может привести к неверным результатам, так как сравнение со значением NULL дает результат UNKNOWN (неизвестно).