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.
Then in the second table I have select ..., null as opt from... I know that I could have an empty string with '' as
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.
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...
select cast (2000 as type of quint) from rdb$database select cast (2000 as int) from rdb$database.
Above is two queries with their results merged by a UNION ALL clause. You will notice that the queries return different columns, one called 'departure' and one called 'arrival'.
I am working on a UNION ALL and receive this error to start: Msg 205, Level 16, State 1, Line 1 All queries combined using a UNION...
Note: A NULL value is different from a zero value or a field that contains spaces.
Существуют специальные операторы IS NULL и IS NOT NULL, которые позволяют производить сравнения с NULLами.
Each SELECT statement within the UNION ALL must have the same number of fields in the result sets with similar data types. What is the difference between