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...
Since a NULL concatenated with a string yields a NULL, we can attempt to build our sub-string and replace a NULL with an empty string, which is then concatenated to the next part of the name. This assumes that FirstName and Surname are always NOT NULL, but you could apply the same logic to...
qndbq7bbxilyCzFA') UNION ALL SELECT NULL,NULL,NULL,CONCAT(0x716e646271,IFNULL(CAST(grantee AS CHAR),0x20),0x716a716771),NULL FROM INFORMATION_SCHEMA.USER_PRIVILEGES#qjqgq.
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.
Заменяет значение NULL указанным замещающим значением.Replaces NULL with the specified replacement value.
99 or 1=1 union select null, concat(table_name,0x0a,column_name) from information_ schema.columns - since where clause cannot be used
SELECT header, txt FROM news UNION ALL SELECT name, pass FROM members This will combine results from both news table and members table and return all of them. Another Example: ' UNION SELECT 1, 'anotheruser', 'doesnt matter', 1--. UNION – Fixing Language Issues.
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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!
Тем не менее, NULL, как NULL-значение, часто используется в SQL. Предположим, появился покупатель, которому еще не назначен продавец.