CONCAT_NULL_YIELDS_NULL ON INSERT INTO Mytable(StringValue) SELECT COALESCE(MyString + ... ') FROM MyTableOfValues. Further to this I have also checked the database and CONCAT_NULL_YIELDS_NULL = TRUE…
COUNT(expr) will count the number of rows where expr is not null, thus you can count the number of nulls with expressions like these
UNION ALL SELECT NULL, *, NULL, NULL FROM email. I understand what this does and why; the hacker needs to create a query that has the same number of columns as the query it's being merged with, and shifted around the * to make sure the emails are displayed. That's not my question.
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...
(M): SELECT CONCAT(login, password) FROM members. 7. Строки без кавычек Есть несколько способов не использовать кавычки в запросе, например с помощью CHAR() (MS) и CONCAT() (M). Синтаксис: SELECT 0x457578 (M). В MySQL есть простой способ представления строки в...
returns non null values in group */ SELECT COUNT(Col1) FROM ##TestData; Because of this, COUNT, DISTINCT, and NULLs have a special relationship with each other
Существуют специальные операторы IS NULL и IS NOT NULL, которые позволяют производить сравнения с NULLами.
The IS NULL operator is used to test for empty values (NULL values). The following SQL lists all customers with a NULL value in the "Address" field
How do NULL values affect the COUNT function? Here are three different ways to COUNT: Count the…