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.
Col_name, test_name ) as (. Select null, 'Actual null' from dual union all select '', 'Null string' from
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...
What is the difference between … and … and why does the latter not work?
How can I run a MySQL query that selects everything that is not null? It would be something like … Do I just remove the all and go..?
Note: A NULL value is different from a zero value or a field that contains spaces.
In SQL, a NULL is never equal to anything, even another NULL. This query won't return anything and in fact will be thrown out by the optimizer when building the plan.
Union select null, null, null, null, null, null -- test all nulls --*/ ). A. DECLARE @ColumnDynamicSQL nvarchar(MAX)