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!
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...
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.
Обработка... Не сейчас. Месяц бесплатно. SGs2 imei (null null) решение проблемы.
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When SET CONCAT_NULL_YIELDS_NULL is ON, concatenating a null value with a string yields a NULL result. For example, SELECT 'abc'
The final question reminded me about a NULL Puzzle, posted by Steve Kass on Jan 2003. I still use it to show others the implication of using "SET ANSI_NULLS OFF".
NULL is a special value that signifies 'no value'. Comparing a column to NULL using the = operator is undefined. Instead, use WHERE IS NULL or WHERE IS NOT
-- By default ANSI_NULLS is off so null comparisons follows the SQL-92 standard.