如果union不能完成，请用dataset.merge

要求：
一个文章表：有PostID(文章编号)，ParentID（关联了的文章PostID）,SourceID(被关联的一篇文章)

原本写了个语句，发觉不能运行。
SELECT PKID, Title, Author, OperateDate, Text, PostID, ParentID, PostID AS SortID
FROM TBL_Post
WHERE (ParentID = 2) AND (PostType = 3 OR
PostType = 7) AND (DeleteFlag = 0)
UNION
SELECT posta.PKID, posta.Title, posta.Author, posta.OperateDate, posta.Text, posta.PostID,
posta.ParentID, postb.PostID AS SortID
FROM TBL_Post posta INNER JOIN
TBL_Post postb ON posta.PostID = postb.SourceID
WHERE posta.ParentID = 2 AND posta.DeleteFlag = 0 AND postb.ParentID = 2 AND
postb.DeleteFlag = 0
ORDER BY SortID

想到dataset. merge,如下成功了

DataSet ds = new DataSet();
string strSQL = String.Format(@"select TBL_Config.BlogID ID , TBL_Config.Author Name
from TBL_Post,TBL_Config
where TBL_Post.Operater = TBL_Config.BlogID
and PostID = {0} And TBL_Config.BlogID > 2",postID);
DataTable dt = JumpDbProvider.Select(strSQL);

dt.PrimaryKey = new DataColumn[1]{dt.Columns["ID"]};
ds.Tables.Add(dt.Copy());

strSQL = String.Format(@" select GroupID ID,GroupName Name
from TBL_Group, TBL_PostRight
where TBL_PostRight.TempID = TBL_Group.GroupID
And IsGroup = 1
and PostID = {0} AND Active = 1",postID);
DataTable dtm = JumpDbProvider.Select(strSQL);

ds.Merge(dtm,false,MissingSchemaAction.Add);

return ds.Tables[0];