I have a sports database with a table groupmembers which have the fields ID, groupID and memberID. I get the memberID from a textbox called txtRemoveGroupMember and the groupID from a checkboxlist. Now I want to delete the rows which have both the groupID and the memberID. I have tried this code:
foreach(ListItem listItem in cblRemoveMemberFromGroup.Items)
{
int memberid = Convert.ToInt32(txtRemoveGroupMember.Text);
int groupid = Convert.ToInt32(listItem.Value);
var removeFromGroup = from gm in dataContext.GroupMembers
where (gm.memberID == memberid) && (gm.groupID == groupid)
select gm;
dataContext.GroupMembers.DeleteOnSubmit(removeFromGroup);
dataContext.SubmitChanges();
}
But I get this error:
Error 7 Argument 1: cannot convert from 'System.Linq.IQueryable<GSI_side.GroupMember>' to 'GSI_side.GroupMember'
And this error:
Error 6 The best overloaded method match for 'System.Data.Linq.Table<GSI_side.GroupMember>.DeleteOnSubmit(GSI_side.GroupMember)' has some invalid arguments
Hope someone can help me figure this out!
You can drag the SPROC to your DBML file and it will generate a rich method in your databasecontext class. Show activity on this post. First, you can find a list of the items you want to delete.
context. ExecuteCommand("TRUNCATE TABLE Entity"); The way you are deleting is taking long because Linq to SQL generates a DELETE statement for each entity, there are other type-safe approaches to do batch deletes/updates, check the following articles: Batch Updates and Deletes with LINQ to SQL.
removeFromGroup
is still of type IQuerable
.
You need to specify an actual GroupMember
to delete.
You could use
GroupMember removeFromGroup = (from gm in dataContext.GroupMembers
where (gm.memberID == memberid) && (gm.groupID == groupid)
select gm).SingleOrDefault();
dataContext.GroupMembers.DeleteOnSubmit(removeFromGroup);
dataContext.SubmitChanges();
Alternatively, if your query returns a collection (from the looks of it, it won't since you are filtering by memberId
) you could use
List<GroupMember> removeFromGroup = (from gm in dataContext.GroupMembers
where (gm.memberID == memberid) && (gm.groupID == groupid)
select gm).ToList();
dataContext.GroupMembers.DeleteAllOnSubmit(removeFromGroup);
dataContext.SubmitChanges();
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