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?
companies
, left join on a subset of users
, using the value from users
to determine ordering. I don't think this is a bad question, just really badly worded - jnylen 2012-04-03 20:53
left join
to select unique rows from one table then right join
to select unique rows from second table and then use union
between both join query to get your desired result - Ankit Sharma 2012-04-04 05:54
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.
table1 -> companies
and table2 -> users
then my query will work as-is - jnylen 2012-04-04 19:33
You will need a JOIN Statement to join another in the SELECT-Statement of table1
Quick example:
SELECT * FROM table2 INNER JOIN table1.id = table2.id WHERE table2.username = 'x1'
You'll find everything you need in the Documentation of JOINs. http://dev.mysql.com/doc/refman/5.1/en/left-join-optimization.html
Create your query like this:
$sql = "SELECT b.companyName FROM table1 a INNER JOIN table2 b ON a.companyName = b.companyName WHERE b.userName = 'x1'";
Then, using PHP, use:
$con = mysql_connect("localhost","peter","abc123");
if (!$con)
{
die('Could not connect: ' . mysql_error());
}
mysql_select_db("my_db", $con);
$result = mysql_query($sql);
while($row = mysql_fetch_array($result))
{
echo $row['companyName'];
echo "<br />";
}
mysql_close($con);
Try this query:
SELECT company_name FROM table2 ORDER BY user_name ASC
In the HTML table, using PHP code:
$result = mysql_query(" SELECT company_name, user_name FROM table2 ORDER BY user_name ASC");
echo "<table>
<tr><th>Company Name</th><th>username</th></tr>";
while($row = mysql_fetch_array($result) {
echo "<tr><td>{$row['company_name']}</td><td>{$row['user_name']}</td></tr>";
}
echo "</table>"
If you're just after the MySQL query for this then something like this would work
SELECT company_name,SUM(IF(user_name='x1',1,0)) as ordering
FROM `table2`
GROUP BY company_name
ORDER BY ordering DESC
But you should look at your schema before you go much further. If you have a column (company_name) in one table that refers to another table you should make that column refer to the PRIMARY KEY of the other table, i.e.
Table1
| # | company_name |
--------------------
| 1 | microsoft |
| 2 | hp |
| 3 | asus |
| 4 | apple |
| 5 | amazon |
| 6 | CCN |
table2
| # | company_id | user_name |
--------------------------------
| 1 | 3 | x1 |
| 2 | 4 | x1 |
| 3 | 2 | x2 |
| 4 | 3 | x2 |
| 5 | 4 | x2 |
This is one of the first things you learn in database design/normalisation. You will need to change your query in this case. Something like this:
SELECT company_name,SUM(IF(user_name='x1',1,0)) as ordering
FROM `table1`
LEFT JOIN `table2` ON table2.company_id=table1.id
GROUP BY company_name
ORDER BY ordering DESC
table2
LEFT JOIN table1
ON table2.companyid=table1.id GROUP BY table1.companyname ORDER BY ordering DESC but it showing me only the commun row not all row in the table please help agai - tony 2012-04-04 16:43