Create a view with column num_rows - MySQL

Question

I need to create a view that has a column named row_num where it will be inserted the row number, just like an auto increment in a normal table.

Let\'s say I\'ve thi

Answer 1

Try to apply this query to your view -

CREATE TABLE testing (
  id int(11) NOT NULL DEFAULT 0,
  country varchar(255) DEFAULT NULL,
  name varchar(255) DEFAULT NULL,
  age int(11) DEFAULT NULL,
  price int(11) DEFAULT NULL,
  PRIMARY KEY (id)
);

INSERT INTO testing(id, country, name, age, price) VALUES
  (1, 'US', 'john', 22, 20),
  (2, 'France', 'Anne', 10, 15),
  (3, 'Sweden', 'Alex', 49, 10),
  (4, 'France', 'Anne', 11, 16);

SELECT
  t1.*, COUNT(*) row_num
FROM testing t1
  LEFT JOIN testing t2
    ON t2.name < t1.name OR (t2.name = t1.name AND t2.id <= t1.id)
 GROUP  BY t1.name, t1.id;

+----+---------+------+------+-------+---------+
| id | country | name | age  | price | row_num |
+----+---------+------+------+-------+---------+
|  3 | Sweden  | Alex |   49 |    10 |       1 |
|  2 | France  | Anne |   10 |    15 |       2 |
|  4 | France  | Anne |   11 |    16 |       3 |
|  1 | US      | john |   22 |    20 |       4 |
+----+---------+------+------+-------+---------+

• This query does not use any user variables, so it wotks in views.
• Additional condition in ON clause helps to implement duplicated values in name field.