Question

I am using VS2005 C# and SQL2005.

I would like to retrieve data from multiple columns and merge them, separating them by comma.

E.g. Data in my SQL Table UserData:

No. | Username | Role 1 | Role 2 | Role 3 |

1 | Jimmy | USER | READONLY | WRITE |

Data I would like to display in my GridView GridView1:

No. | Username | Roles |

1 | Jimmy | USER, READONLY, WRITE |

How can I use a SELECT statement to merge data from the 3 columns and merge them, separating the data by commas and list them in the GridView?

Thank you

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EDIT

I have tried using the method provided by Shark and Mun, but I would like to remove the commas if the data in a Role column is empty.

Situation now is that Roles column will look like this if Role 2 and Role 3 is empty:
USER,,

May I know how can I group , into the variable as well so it will not display if the value is empty?

Answer 1

Here is the SQL query:

select
    username,
    isnull(nullif([role 1], '') + ', ', '') + 
    isnull(nullif([role 2], '') + ', ', '') + 
    isnull(nullif([role 3], ''), '') as Roles
from UserData

And then for your grid view code:

SqlConnection conn = new SqlConnection(YourConnectionStringHere);
SqlCommand cmd = new SqlCommand();
cmd.Connection = conn;
cmd.CommandText = 
    "select " +
    "    username, " +
    "    isnull(nullif([role 1], '') + ', ', '') + " +
    "    isnull(nullif([role 2], '') + ', ', '') + " +
    "    isnull(nullif([role 3], ''), '') as Roles " +
    "from UserData";

SqlDataAdapter sda = new SqlDataAdapter(cmd);
Datatable YourData = new DataTable();

try
{
    sda.Fill(YourData);

    GridView1.DataSource = YourData;
    GridView1.Bind();
}
catch
{
    sda.Dispose();
    // handle your error
}