CLR: Multi Param Aggregate, Argument not in Final Output?
- by OMG Ponies
Why is my delimiter not appearing in the final output? It's initialized to be a comma, but I only get ~5 white spaces between each attribute using:
SELECT [article_id]
, dbo.GROUP_CONCAT(0, t.tag_name, ',') AS col
FROM [AdventureWorks].[dbo].[ARTICLE_TAG_XREF] atx
JOIN [AdventureWorks].[dbo].[TAGS] t ON t.tag_id = atx.tag_id
GROUP BY article_id
The bit for DISTINCT works fine, but it operates within the Accumulate scope...
Output:
article_id | col
-------------------------------------------------
1 | a a b c
I only have rudimentary C# API knowledge...
C# Code:
using System;
using System.Data;
using System.Data.SqlClient;
using System.Data.SqlTypes;
using Microsoft.SqlServer.Server;
using System.Xml.Serialization;
using System.Xml;
using System.IO;
using System.Collections;
using System.Text;
[Serializable]
[SqlUserDefinedAggregate(Format.UserDefined, MaxByteSize = 8000)]
public struct GROUP_CONCAT : IBinarySerialize
{
ArrayList list;
string delimiter;
public void Init()
{
list = new ArrayList();
delimiter = ",";
}
public void Accumulate(SqlBoolean isDistinct, SqlString Value, SqlString separator)
{
delimiter = (separator.IsNull) ? "," : separator.Value ;
if (!Value.IsNull)
{
if (isDistinct)
{
if (!list.Contains(Value.Value))
{
list.Add(Value.Value);
}
}
else
{
list.Add(Value.Value);
}
}
}
public void Merge(GROUP_CONCAT Group)
{
list.AddRange(Group.list);
}
public SqlString Terminate()
{
string[] strings = new string[list.Count];
for (int i = 0; i < list.Count; i++)
{
strings[i] = list[i].ToString();
}
return new SqlString(string.Join(delimiter, strings));
}
#region IBinarySerialize Members
public void Read(BinaryReader r)
{
int itemCount = r.ReadInt32();
list = new ArrayList(itemCount);
for (int i = 0; i < itemCount; i++)
{
this.list.Add(r.ReadString());
}
}
public void Write(BinaryWriter w)
{
w.Write(list.Count);
foreach (string s in list)
{
w.Write(s);
}
}
#endregion
}
