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.
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...
I've tried setting the pointer to null but keep getting a segmentation error.
E.g. null + null + 1 = 1 null + null + null = null. The problem is that the first expression yields null.
Union select null, null, null, null, null, null -- test all nulls --*/ ). A. DECLARE @ColumnDynamicSQL nvarchar(MAX)
NULL is special in SQL. NULL indicates that the data is unknown, inapplicable or even does not exist.
In R language, NULL … Continue reading R null values: NULL, NA, NaN, Inf.