Question

I’m new to MySQL and PHP. I have two tables, one to hold all the company names and the other table has only the company name below the user:

Table 1
| # | Company name |
--------------------
| 1 | Microsoft    |
| 2 | HP           |
| 3 | Asus         |
| 4 | Apple        |
| 5 | Amazon       |
| 6 | CCN          |

table 2
| # | Company name | User name |
--------------------------------
| 1 | Asus         |   x1      |
| 2 | Apple        |   x1      |
| 3 | HP           |   x2      |
| 4 | Asus         |   x2      |
| 5 | Apple        |   x2      |

I need to create a query that achieves the following. First of all the companies are shown which are associated with a specific user (say Asus and Apple for user x1). After that, the remaining companies from table 1 are shown.

For example, the result of the query I’m looking for, for user X1 will display the rows in this way:

| # | Company name |
--------------------
| 1 | Asus         |
| 2 | Apple        |
| 3 | Microsoft    |
| 4 | HP           |
| 5 | Amazon       |
| 6 | CCN          |

How can I achieve this?

Answer 1

It looks like you want to include all companies, but for a given user, list the companies associated with that user first. If that’s the case, you do not want to use an INNER JOIN.

Here’s some SQL that should work. I’ve provided reasonable table and field names since you didn’t give those. I’m also assuming that you have a reasonably sane table design with no duplicate rows.

SELECT c.company_name,

  CASE
    WHEN u.company_name IS NULL THEN 'N'
    ELSE 'Y'
  END AS user_has_company

FROM companies c

LEFT JOIN (
  SELECT *
  FROM users
  WHERE user_name = 'x1'
) u
ON u.company_name = c.company_name

ORDER BY user_has_company DESC, c.company_name

This query will return an extra column – user_has_company. I’d use that to indicate whether the current user is associated with a given company, but you can ignore it if you want.