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 concat_ws('-', Firstname, Middlename, Surname) AS example_column FROM example_table.
COUNT(*) will include NULLS. COUNT(column_or_expression) won't. This means COUNT(any_non_null_column) will give the same as COUNT(*) of course because there are no NULL values to cause differences. Generally, COUNT(*) should be better because any index can be used...
Синтаксис функции COUNT: SELECT COUNT(expression) FROM table WHERE predicates; Функция COUNT принимает один из нескольких параметров
select (select count(*) from tablea)+(select count(*) from tableb) from dual. Not saying it's better (I can't test it right now so it might not even work!)
(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...
Сюда входят значения NULL и повторяющиеся значения.This includes NULL values and duplicates.
Вы можете использовать функцию CONCAT в команде SELECT
SELECT DISTINCT Examples. The following SQL statement selects only the DISTINCT values from the "Country" column in the "Customers" table