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.
I have a table with three fields, FirstName, LastName and Email. Here's some dummy data: … Now, if I do: … Vitals for Joe is null, as there is a single null field. How do you overcome this behaviour?
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.
A field with a NULL value is a field with no value. If a field in a table is optional, it is possible to insert a new record or update a record without adding a value to this
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?
The concept of the NULL value is a common source of confusion for newcomers to SQL, who often think
Заметка про NULL. Всем привет! Долго думал, что бы написать полезного про Оракл, перепробовал кучу тем.
SQL’s NULL indicates absent data. NULL propagates through expressions and needs distinct comparison operators.
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