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.
Then in the second table I have select ..., null as opt from... I know that I could have an empty string with '' as
Note: A NULL value is different from a zero value or a field that contains spaces.
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...
The IS NOT NULL condition is used in SQL to test for a non-NULL value. It returns TRUE if a non-NULL value is found, otherwise it returns FALSE. It can be used in a SELECT, INSERT, UPDATE, or DELETE statement.
NULL handling in the Oracle database is even more special.
The NOT NULL constraint specifies that NULL is not an allowable value. For example, in the following statement, CREATE TABLE Customer (SID integer NOT NULL
NULL values represent missing unknown data. By default, a table column can hold NULL values.
Is there a way to set a char variable to 0 or null or something so that it will basically reset my control variable.
R language supports several null-able values and it is relatively important to understand how these