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...
As @Prdp noted, the answer is RDBMS-specific. What is specific is whether the server treats a zero-length string as being equivalent to NULL, which determines whether concatenating a NULL yields a NULL or not. Generally COALESCE is most concise for PostgreSQL-style empty string handling, and...
SELECT * FROM table. And then I have to filter out the null values with a php loop.
Синтаксис функции COUNT: SELECT COUNT(expression) FROM table WHERE predicates; Функция COUNT принимает один из нескольких параметров
select count(value_x) People from table_a union select count(distinct value_x) People from table_b; We are currently getting: People 24998 23965. We have placed a break on report and computed a sum of count, but that's not really what we want. We would like to see just
mysql> SELECT * FROM worker WHERE name LIKE '%ex'
Сюда входят значения NULL и повторяющиеся значения.This includes NULL values and duplicates.
(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...
SELECT DISTINCT Examples. The following SQL statement selects only the DISTINCT values from the "Country" column in the "Customers" table