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.
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...
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.
Then in the second table I have select ..., null as opt from... I know that I could have an empty string with '' as
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...
What is the difference between … and … and why does the latter not work?
Does the mysql UNION and UNION ALL operator always remove rows that have a NULL in them? I am doing a UNION of two SELECT statements - one of which may return a row with a NULL in it.
Note: A NULL value is different from a zero value or a field that contains spaces.
ID in both tables will never be NULL. It IS possible that one of the tables may have ID values that are NOT in the other table.
R language supports several null-able values and it is relatively important to understand how these values behave, when making data pre-processing and