Very Easy
Specify column order I
Consider the following table ecommerce_users which contains a list of all the registered users of an ecommerce website.
+-------------------+------------+-----------+-----------------------------------+-----+--------+----------------+
| ecommerce_user_id | first_name | last_name | email | age | gender | country |
+-------------------+------------+-----------+-----------------------------------+-----+--------+----------------+
| 1 | Max | Jenkins | [email protected] | 34 | M | United Kingdom |
| 2 | Lucy | Hennaway | [email protected] | 28 | F | United Kingdom |
| 3 | Rob | Jones | [email protected] | 30 | M | United Kingdom |
| ... | ... | ... | ... | ... | ... | ... |
+-------------------+------------+-----------+-----------------------------------+-----+--------+----------------+
Write a query that returns the email and first_name columns from this table, in that specific order.
EXPECTED OUTPUT
+-----------------------------------+------------+
| email | first_name |
+-----------------------------------+------------+
| [email protected] | Max |
| [email protected] | Lucy |
| [email protected] | Rob |
| ... | ... |
+-----------------------------------+------------+
Remember, the order of the columns in your SELECT clause determines the order in which they appear in the results. For example, writing:
SELECT col1, col2 FROM table1
will produce a table in which col1 appears first, followed by col2.
If you swap the order of the columns, however:
SELECT col2, col1 FROM table1
you'll get a table in which col2 appears first, followed by col1.
SELECT
email,
first_name
FROM ecommerce_users