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.
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...
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'.
Then in the second table I have select ..., null as opt from... I know that I could have an empty string with '' as
In advance, I would like to say thanks for the help. This is a great community and I've found many programming answers here. I have a table with multiple columns, 5 of which contain dates or null.
What is the difference between … and … and why does the latter not work?
Note: A NULL value is different from a zero value or a field that contains spaces. A field with a NULL value is one that has been left blank during record creation!
Тем не менее, NULL, как NULL-значение, часто используется в SQL. Предположим, появился покупатель, которому еще не назначен продавец. Чтобы констатировать этот факт, нужно ввести значение NULL в поле snum, а реальное значение включить туда позже...
R language supports several null-able values and it is relatively important to understand how these values behave, when making data pre-processing and data munging. In general, R supports: NULL NA NaN Inf / -Inf NULL is an object and is returned when an expression or function results in an...