Concatenate two columns based upon another column in SQL Server 2005

Question

I have database as follows

A     B
1   ereee
2   ereee
2   sdfsd
3   nere
1   sdfsd

I want to have a data which will be as follows

A     B
1   ereee,sdfsd
2   ereee,sdfsd
3   nere

what is the query?

Answer 1

Your question didn't specify what kind of database. The following works for MySQL and perhaps a few others:

GROUP_CONCAT(expr)
This function returns a string result with the concatenated non-NULL values from a group.

https://dev.mysql.com/doc/refman/5.0/en/group-by-functions.html#function_group-concat

SELECT A, GROUP_CONCAT(B SEPARATOR ',') AS B 
FROM table
GROUP BY A

Update 2015-07-30 09:43 +0000

Since it's been made clear that this is about SQL Server 2005, the question might be a duplicate of this:

Simulating group_concat MySQL function in Microsoft SQL Server 2005?